【单选题】
38为了使放大器带负载能力强，一般引入___负反馈。
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【单选题】
41为了提高三极管放大电路的输入电阻，采用___负反馈 i=i1+i2
【单选题】
42为了稳定输出电流，采用___负反馈。
【单选题】
43为了改善放大器的动态性能，应该引入___电路。
A. 直流负反馈
B. 交流负反馈
C. 电压负反馈
D. 电流负反馈
【单选题】
44为了稳定放大器的静态工作点，应该引入___电路。
A. 直流负反馈
B. 交流负反馈
C. 电压负反馈
D. 电流负反馈
【单选题】
45共模抑制比是差分放大电路的一个主要技术指标，它反映放大电路___能力。
A. 放大差模抑制共模
B. 输入电阻高
C. 输出电阻低
【单选题】
46差分放大电路是为了___而设置的。
A. 稳定Au
B. 放大信号
C. 抑制零点漂移
【单选题】
47分析运放的“虚短”是指是___。
A. U-≈U+
B. I-≈I+≈0
C. U0=Ui
D. U-≈U+≈0
【单选题】
48分析运放的“虚断”是指是___。
A. U-≈U+
B. I-≈I+≈0
C. I-≈I+
D. U-≈U+≈0
【单选题】
51两级放大电路，Au1=-40，Au2=-50，若输入电压U1=5mv，则输出电压Uo为 ___
A. -200mv；
B. -250mV；
C. 10V；
D. 100V
【单选题】
52通用型集成运放的输入级多采用___。
A. 共基接法
B. 共集接法
C. 共射接法
D. 差分接法
【单选题】
53理想运放的两个重要性质是___。
A. 虚短与虚地
B. 虚断与虚短
C. 断路与短路
【单选题】
54振荡器的输出信号最初由___而来的。
A. 基本放大器
B. 选频网络
C. 干扰或噪声信号
【单选题】
55产生正弦波自激震荡的稳定条件是___。
A. 引入正反馈
B. |AF|≥1
C. AF=1
【单选题】
56从结构上来看，正弦振荡电路是一个 ___ 。
A. 有输入信号的负反馈放大器；
B. 没有输入信号的带选频网络的正反馈放大器；
C. 没有输入信号的不带选频网络的正反馈放大器。
【单选题】
57对频率稳定度要求较高的振荡器，要采用： ___ 。
A. LC振荡电路；
B. RC振荡电路；
C. RL振荡电路；
D. 石英晶体振荡电路。
【单选题】
58在甲类、乙类、甲乙类放大电路中，其导通角分别为___
A. 小于180 O、180 O、360O
B. 360O、180 O、小于180 O。
C. 180 O、小于180 O、360O
【单选题】
W78XX系和列W79XX系列引脚对应关系为 ___ 。
A. 一致；
B. 1脚与3脚对调，2脚不变；
C. 1、2对调。
【单选题】
60两个β相同的晶体管组成复合管后，其电流放大系数约为 ___ 。
【单选题】
1三极管的开关特性是___。
A. 截止相当于开关接通
B. 放大相当于开关接通
C. 饱和相当于开关接通
D. 截止相当于开关断开，饱和相当于开关接通
【单选题】
2数字集成门电路，目前生产最多应用最普遍的门电路是___
【单选题】
3由一个三极管组成的基本门电路是___。
【单选题】
4在遥测系统中，需通过___把非电量的变化转变为电信号。
A. 电阻器、
B. 电容器、
C. 传感器、
D. 晶体管
【单选题】
5半导体发光数码管由___个条状的发光二极管组成。
【单选题】
6“有0出1，全1出0”属于___
A. 与逻辑
B. 或逻辑
C. 非逻辑
D. 与非逻辑
【单选题】
7二进制数11101转化成十进制数为___
【单选题】
8TTL系列集成芯片工作电源电压的典型值是___。
A. 18V
B. 5V
C. 3V
D. 10V
【单选题】
10以下表达式中符合逻辑运算法则的是___。
A. 1+1=10
B. A+A=2A
C. A+=1.
D. A·=1
【单选题】
11对于TTL与非门闲置输入端的处理，不可以___
A. 与有用输入端并联
B. 通过电阻3kΩ接电源
C. 接地
D. 接电源
【单选题】
12十线/四线优先编码器74LS147所用的输出代码为___。
A. 5421BCD码
B. 格雷码
C. 8421BCD码
D. 余3码
【单选题】
13为实现“线与”逻辑功能，应选用___
A. OC门
B. 与门
C. 异或门
D. 同或门
【单选题】
14和逻辑式A+ABC相等的式子是___
【单选题】
15逻辑函数的表示方法中具有唯一性的是___
A. 真值表
B. 表达式
C. 逻辑图
D. 卡诺图
【单选题】
16与模拟电路相比，数字电路主要的优点是___。
A. 容易设计
B. 通用性强
C. 抗干扰能力强
【单选题】
17某门电路的输入输出波形如图所示，试问此逻辑门的功能是___。
【单选题】
18以下电路中常用于总线应用的有___。
A. TSL门
B. OC门
C. 漏极开路门
D. CMOS与非门
【单选题】
逻辑表达式Y=AB可以用___实现。
A. 正或门
B. 正非门
C. 正与门
D. 负或门
【单选题】
20TTL电路在正逻辑系统中，以下各种输入中___相当于输入逻辑“0”。
A. 悬空
B. 通过电阻2.7kΩ接电源
C. 通过电阻2.7kΩ接地
D. 通过电阻510Ω接地
【单选题】
21对于TTL与非门闲置输入端的处理，不可以___。
A. 接电源
B. 通过电阻3kΩ接电源
C. 接地
D. 与有用输入端并联
【单选题】
22STTL数字集成电路与CMO数字集成电路相比突出的优点是___。
A. 微功耗
B. 高速度
C. 高抗干扰能力
D. 电源范围宽
推荐试题
【单选题】
Which statements about the native VLAN is true ？___
A. It is susceptible to VLAN hopping attacks.
B. It is the Cisco recommended VLAN for switch-management traffic
C. It is most secure when it is a ssigned to vLAn 1.
D. It is the cisco-recomme nded vlan for user traffic
【单选题】
There are two versions of IKE:IKEv1 and IKEv2. Both IKEv1 and IKEv2 protocols operate in phases IKEv1 operates in two phases. IKEv2 operates in how many phases？___
【单选题】
What does the dh group refer to？___
A. length of key for hashing C
B. length of key for encryption
C. tunnel lifetime key
D. length of key for key exchange
E. length of key for authentication
【单选题】
Which path do you follow to enable aaa through the SDM ？___
A. Configure Tasks > AAA
B. Configure > Addition Authentication > AAA
C. Configure > AAA
D. Configure > Additional Tasks > AAA
E. Configure Authentication > AAA
【单选题】
which technology cloud be used on top of an MPLS VPN to add confidentiality ？___
A. IPsec
B. 3DES
C. AES
D. SSL
【单选题】
Which term is most closely aligned with the basic purpose of a SIEM solution? ___
A. Non-Repudiation
B. Accountability
C. Causality
D. Repudiation
【单选题】
You have just deployed SNMPv3 in your environment， Your manager asks you to make sure that our SNMP agents can only talk to the SNMP Manager. What would you configure on your SNMI agents to satisfy this request？___
A. A SNMP View containing the SNMP managers
B. Routing Filter with the SNMP managers in it applied outbound
C. A standard ACL containing the SNMP managers applied to the SNMP configuration
D. A SNMP Group containing the SNMP managers
【单选题】
Which feature prevents loops by moving a nontrunking port into an errdisable state when a BPDU is received on that port？___
A. BPDU filte
B. DHCP snooping
C. BPDU guard
D. Port Fast
【单选题】
Which command enables port security to use sticky MAC addresses on a switch？___
A. switchport port-security violation restrict
B. switchport port-security mac-address sticky
C. switchport port-security violation protect
D. switchport port-security
【单选题】
When you edit an IPS subsignature， what is the effect on the parent signature and the family of subsignatures？___
A. The change applies to the parent signature and the entire family of subsignatures
B. The change applies to the parent signature and the subsignature that you edit
C. The change applies only to subsignatures that are numbered sequentially after the subsignature that you edit
D. Other signatures are unaffected， the change applies only to the subsignature that you dit
【单选题】
Which type of mechanism does Cisco FirePOWER de ploy to protect ag detected moving across other networks？___
A. antivirus scanning
B. policy-based
C. reputation-based
D. signature-based
【单选题】
What action must you take on the ise to blacklist a wired device？___
A. Locate the switch through which the device is connected and push an a cl restricting all access by the device
B. Issue a CoA request for the de vice's mac address to each access switch in the network
C. Revoke the device's certificate so it is unable to authenticate to the network
D. Add the device's MAc address to a list of black listed devices
【单选题】
Which type of firewall can perform deep packet inspection？___
A. packet-filtering firewall
B. stateless firewall
C. application firewall
D. personal firewall
【单选题】
What is the main purpose of Control Plane Policing？___
A. to prevent exhaustion of route-proce ssor resources
B. to organize the egress packet queues
C. to define traffic classes
D. to maintain the policy map
【单选题】
Which attack can be prevented by OSPF authentication？___
A. smurf attack
B. IP spoofing attack
C. denial of service attack
D. buffer overflow attack
【单选题】
What is the best definition of hairpinning？___
A. ingress traffic that traverses the outbound interface on a device
B. traffic that enters one interface on a device and that exits through another interface
C. traffic that enters and exits a device through the same interface
D. traffic that tunnels through a device interface
【单选题】
Which SNMPv3 security level provides authentication using HMAC with MD5， but does not use encryption？___
A. authPriv
B. authNo Priv
C. noAuthNoPriv
D. NoauthPriv
【单选题】
You have implemented a dynamic blacklist， using security intelligence to block illicit network activity. However， the blacklist contains several approved connections that users must access for usiness pur poses. Which action can you take to retain the blacklist while allowing users to access the approve d sites？___
A. Create a whitelist and manually add the approved addresses.
B. Disable the dynamic blacklist and deny the specif ic address on a whitelist while permitting the others
C. Edit the dynamic blacklist to remove the approved addresses
D. Disable the dynamic blacklist and create a static blacklist in its place
【单选题】
When connecting to an external resource,you must change a source IP address to use one IP address from a range of 207.165.201.1 to 207.165.1.30. Which option do you implement ?___
A. dynamic source NAT that uses an IP ad dress as a mapped source
B. static destination NAT that uses a subnet as a real de stination
C. dynamic source NAT that uses a range as a mapped source
D. static destination NAT that uses a subnet as a real source
【单选题】
Refer to the exhibit. 【nat（ins，any）dynamic interface】Which ty pe of NaT is configured on a Cisco ASA？___
A. dynamic NAT
B. source identity NAT
C. dynamic PAT
D. identity twice NAT
【单选题】
Which mitigation technology for web-based threats prevents the removal of confidential data from the network？___
A. CTA
B. DCA
C. AMP
D. DLP
【单选题】
Refer to the exhibit. What is the effect of the given configuration？___
A. It establishes the preshared key for the switch
B. It establishes the preshared key for the firewall.
C. It establishes the preshared key for the Cisco ISE appliance
D. It establishes the preshared key for the router.
【多选题】
What are two major considerations when choosing between a SPAN and a TAP when plementing IPS？___
A. the type of analysis the iS will perform
B. the amount of bandwidth available
C. whether RX and TX signals will use separate ports
D. the way in which media errors will be handled
E. the way in which dropped packets will be handled
【多选题】
What are two direct-to-tower methods for redirecting web traffic to Cisco Cloud Web Security？___
A. third-party proxies
B. Cisco Catalyst platforms
C. Cisco NAC Agent
D. hosted PAC files
E. CiSco ISE
【多选题】
Which three descriptions of RADIUS are true？ ___
A. It uses TCP as its transport protocol.
B. Only the password is encrypted
C. It supports multiple transport protocols
D. It uses UDP as its transport protocol
E. It combines authentication and authorization
F. It separates authentication，authorization，and accounting
【多选题】
Which two configurations can prevent VLAN hopping attack from attackers at VLAN 10？___
A. using switchport trunk native vlan 10 command on trunk ports
B. enabling BPDU guard on all access ports
C. creating VLAN 99 and using switchport trunk native vlan 99 command on trunk ports
D. applying ACl between VLAN
E. using switchport mode access command on all host ports
F. using switchport nonegotiate command on dynamic desirable ports
【多选题】
What are two features of transparent firewall mode ___
A. It conceals the presence of the firewall from attackers
B. It allows some traffic that is blocked in routed mode
C. It enables the aSA to perform as a router.
D. It acts as a routed hop in the network.
E. It is configured by default
【多选题】
Which two models of A sa tend to be used in a data center？___
A. 5555X
B. 5585X
C. ASA service module
D. 5512X
E. 5540
F. 5520
【多选题】
Which two statements about hardware-based encrption are true？___
A. It is widely accessible
B. It is potentially easier to compromise than software-based encryption. It requires minimal configuration
C. It requires minimal configuration
D. It can be implemented without impacting performance
E. It is highly cost-effective
【多选题】
In which two modes can the Cisco We b Security appliance be de ployed？___
A. as a transparent proxy using the Secure Sockets Layer protocol
B. as a transparent proxy using the Web Cache Communication Protocol
C. explicit proxy mode
D. as a transparent proxy using the Hyper Text Transfer Protocol
E. explicit active mode
【单选题】
1．三相刀开关的图形符号与交流接触器的主触点符号是___。
A. 一样的
B. 可以互换
C. 有区别的
D. 没有区别
【单选题】
5．熔断器的作用是___。
A. 短路保护
B. 过载保护
C. 失压保护
D. 零压保护
【单选题】
6．热继电器的作用是___。
A. 短路保护
B. 过载保护
C. 失压保护
D. 零压保护
【单选题】
7．交流接触器的作用是可以___接通和断开负载。
【单选题】
8．三相异步电动机的启停控制线路由电源开关、熔断器、___、热继电器、按钮等组成。
A. 时间继电器
B. 速度继电器
C. 交流接触器
D. 漏电保护器
【单选题】
9．三相异步电动机的启停控制线路中需要有___、过载保护和失压保护功能。
A. 短路保护
B. 超速保护
C. 失磁保护
D. 零速保护
【单选题】
10维修电工以___、安装接线图和平面布置图最为重要。
A. 电气原理图
B. 电气设备图
C. 电气安装图
D. 电气组装图
