相关试题
【单选题】
牌号为R317的焊条是___焊条
A. 低温钢
B. 结构钢
C. 奥氏体不锈钢
D. 珠光体耐热钢
【单选题】
珠光体耐热钢焊前局部预热必须保证预热宽度，焊缝两侧各大于所焊壁厚的4倍，且至少不小于 ___mm
A. 100
B. 150
C. 200
D. 250
【单选题】
珠光体耐热钢焊条电弧焊焊后应立即进行___
A. 高温回火
B. 低温回火
C. 退火
D. 正火
【单选题】
牌号为W707的焊条是___焊条
A. 结构钢
B. 低温钢
C. 奥氏体不锈钢
D. 奥氏体耐热钢
【单选题】
___不是用于-40～-100℃的低合金低温钢焊接工艺特点
A. 一般可不预热
B. 焊前预热
C. 耍控制层间温度不大于200~300℃
D. 焊后进行热处理，细化晶粒消除应力
【单选题】
2Cr13钢是___型不锈钢
A. 马氏体
B. 铁素体
C. 奥氏体
D. 奥氏体-铁素体
【单选题】
奥氏体不锈钢的电阻率___
A. 比碳钢低
B. 比碳钢高
C. 与碳钢一样
D. 略低于碳钢
【单选题】
加热温度 ___℃是不锈钢晶间腐蚀的危险温度区，或称敏化温度区
A. 150-450℃
B. 450-850℃
C. 850-950℃
D. 950-1050℃
【单选题】
超低碳奥氏体不锈钢碳的质量分数为≤___
A. 0.14%
B. 0.08%
C. 0.06%
D. 0.03%
【单选题】
___不是奥氏体不锈钢焊接时为减小焊接残余应力采取的工艺措
A. 采用小线能量
B. 焊前预热
C. 采用短焊道焊
D. 适当的焊后锤击施
【单选题】
___不是奥氏体不锈钢焊接时防止热裂纹的措施
A. 严格限制焊缝中硫、磷等杂质的质量分数
B. 选用双相组织的焊条
C. 采用小线能量，多层多道焊
D. 选用酸性焊条
【单选题】
___不是奥氏体不锈钢的焊接工艺特点
A. 不能进行预热和后热工艺
B. 采用小线能量，小电流快速焊
C. 要快速冷却
D. 焊前预热
【单选题】
___不是奥氏体不锈钢焊条电弧焊工艺操作必须遵循的原则
A. 选用碱性焊条，采用直流反接
B. 采用多层多道焊
C. 采用焊条不摆动的窄道焊
D. 控制焊道间温度，冷却到60℃左右再焊下一道
【单选题】
焊接热裂纹可看成是拉应力和___两者联合作用而形成的
A. 低熔点共晶
B. 氢
C. 淬硬组织
D. 氮化物
【单选题】
___不是促成冷裂纹的主要因素
A. 钢种淬硬倾向大，产生淬硬组织
B. 接头受到的拘束应力大
C. 较多扩散氢的存在和聚集
D. 较多氧的存在和聚集
【单选题】
按规定参数烘干焊条、焊剂是防止 ___的措施之一
A. 夹渣
B. 气孔
C. 热裂纹
D. 未焊透
【单选题】
工件表面锈皮未清除干净会引起___
A. 气孔
B. 再热裂纹
C. 咬边
D. 弧坑
【单选题】
___不是产生夹渣的原因
A. 焊层、焊道之间清渣不干净
B. 焊接电流太小
C. 焊接速度太快
D. 未按规定参数烘干焊条、焊剂
【单选题】
___不是产生未焊透的原因
A. 坡口钝边过大,间隙太小
B. 焊接电流过小,焊接速度过快
C. 短弧焊接
D. 焊接时电弧磁偏吹
【单选题】
钨极直径太小、焊接电流太大是产生 ___的原因之一
A. 夹钨
B. 热裂纹
C. 再热裂纹
D. 未焊透
【单选题】
下列缺陷一般除___外，均需进行返修
A. 焊缝表面有裂纹
B. 焊缝内部有超过图样和标准规定的缺陷
C. 焊缝表面有气孔、夹渣
D. 深度不大于0.5mm、连续长度不大于100mm的咬边
【单选题】
___不是焊接检验的目的
A. 发现焊接缺陷
B. 检验焊接接头的性能
C. 确保产品的焊接质量
D. 测定焊接残余应力
【单选题】
___不是非破坏性检验
A. 致密性试验
B. 水压试验
C. 着色检验
D. 金相检验
【单选题】
___不属于破坏性检验
A. 水压试验
B. 弯曲试验
C. 冲击试验
D. 耐腐蚀试验
【单选题】
在射线探伤胶片上呈圆形、椭圆形黑点，其黑度一般是中心处较大并均匀地向四周边缘减小的缺陷是___
【单选题】
在射线探伤胶片上呈单独黑点，外形不太规则，带有棱角，黑度较均匀的缺陷是___
A. 点状夹渣
B. 条状夹渣
C. 气孔
D. 未熔合
【单选题】
我国射线探伤标准规定，焊缝质量分为四个等级， ___是1级焊缝内允许存在缺陷
A. 气孔
B. 未熔合
C. 未焊透
D. 条状夹渣
【单选题】
我国射线探伤标准规定，焊缝质量分为四个等级，___是2级焊缝内允许存在的缺陷
【单选题】
单相桥式可控整流电路电感性负载时，控制角α的移相范围是___。
A. 0～90°
B. 0～360°
C. 0～180°
D. 0～270°
【单选题】
单相桥式可控整流电路电阻性负载，晶闸管中的电流平均值是负载的___倍。
【单选题】
晶闸管两端并联压敏电阻的目的是实现___。
A. 过压保护
B. 过流保护
C. 防止冲击电流
D. 防止冲击电压
【单选题】
断路器中过电流脱扣器的额定电流应该大于等于线路的___。
A. 最大过载电流
B. 最大短路电流的
C. 最大允许电流
D. 最大负载电流
【单选题】
接触器的额定电压应不小于主电路的___。
A. 短路电压
B. 工作电压
C. 最大电压
D. 峰值电压
【单选题】
对于工作环境恶劣、启动频繁的异步电动机，所用热继电器热元件的额定电流可选为电动机额定电流的___倍。
A. 0.95～1.05
B. 1.05～1.15
C. 1.15～1.50
D. 0.85～0.95
【单选题】
中间继电器的选用依据是控制电路的___、电流类型、所需触点的数量和容量等。
A. 电压等级
B. 阻抗大小
C. 短路电流
D. 绝缘等级
【单选题】
根据机械与行程开关传力和位移关系选择合适的___。
A. 电流类型
B. 电压等级
C. 接线型式
D. 头部型式
【单选题】
用于指示电动机正处在旋转状态的指示灯颜色应选用___。
【单选题】
BK系列控制变压器适用于机械设备中一般电器的___、局部照明及指示电源。
A. 控制电源
B. 电动机
C. 油泵
D. 压缩机
推荐试题
【单选题】
____ you know, David has been well lately.
A. Which
B. As
C. What
D. When
【单选题】
The harder you study, _____ you will learn.
A. much
B. many
C. the more
D. much more
【单选题】
They got there an hour _____ than the others.
A. early
B. much early
C. more early
D. earlier
【单选题】
The grey building is the place where the workers live, and the white building is the place where the spare parts ____ .
A. are producing
B. are produced
C. produced
D. being produced
【单选题】
Once environmental damage ______, it takes many years for the system to recover.
A. is to do
B. does
C. had done
D. is done
【单选题】
We worked hard and completed the task ___.
A. in the time
B. on the time
C. ahead of time
D. before time
【单选题】
I didn't expect you to turn _____ at the meeting yesterday.
A. up
B. to
C. out
D. over
【单选题】
I like the teacher _______ classes are very interesting and creative.
A. which
B. who
C. whose
D. what
【单选题】
When Lily came home at 5 p. m. yesterday, her mother ______ dinner in the kitchen.
A. cooked
B. was cooking
C. cooks
D. has cooked
【单选题】
I don’t know the park, but it's _____ to be quite beautiful.
A. said
B. told
C. spoken
D. talked
【单选题】
Mike is better than Peter ____. swimming.
【单选题】
The young lady coming over to us ______ our English teacher; the way she walks tells us that!
A. must be
B. can be
C. would be
D. could be
【单选题】
Eggs, though rich in nourishments, have ______ of fat.
A. a large number
B. the large number
C. a large amount
D. the large amount
【单选题】
Neither John ______his father was able to wake up early enough to catch the morning train.
A. nor
B. or
C. but
D. and
【单选题】
Jane's dress is similar in design ______ her sister's.
A. like
B. with
C. to
D. as
【单选题】
His salary as a driver is much higher than ________.
A. a porter
B. is a porter
C. as a porter
D. that of a porter
【单选题】
_____ these honours he received a sum of money.
A. Except
B. But
C. Besides
D. Outside
【单选题】
Would you let ____ to the park with my classmate, Mum?
A. me go
B. me going
C. I go
D. I going
【单选题】
I have been looking forward to_____ from my parents.
A. hear
B. being heard
C. be heard
D. hearing
【单选题】
The manager will not _____ us to use his car.
A. have
B. let
C. agree
D. allow
【单选题】
_____ her and then try to copy what she does.
A. Mind
B. See
C. Stare at
D. Watch
【单选题】
Will you ___ me a favor, please?
A. do
B. make
C. bring
D. give
【单选题】
It's bad _____ for you to smoke in the public places where smoking is not allowed.
A. behavior
B. action
C. manner
D. movement
【单选题】
The computer system ____ suddenly while he was searching for information on the Internet.
A. broke down
B. broke out
C. broke up
D. broke in
【单选题】
If she wants to keep slim, she must make a ___ in her diet
A. change
B. turn
C. run
D. go
【单选题】
______ the War of Independence, the United States was an English colony.
A.
B. efore B. At
C. In
D. Between
【单选题】
A police officer claimed he had attempted to ____ paying his fare.
A. avoid
B. reject
C. refuse
D. neglect
【单选题】
While I was in the university, I learned taking photos, ______ is very useful now for me.
A. it
B. which
C. that
D. what
【单选题】
He is not seriously ill, but only a ____ headache.
A. obvious
B. delicate
C. slight
D. temporary
【单选题】
On average, a successful lawyer has to talk to several ____ a day.
A. customers
B. supporters
C. guests
D. clients
【单选题】
What is the train ____ to Birmingham?
A. fee
B. tip
C. fare
D. cost
【单选题】
You shouldn't ______ your time like that, Bob, and was cold yesterdak tonight.
A. cut
B. do
C. kill
D. kick
【单选题】
Both the kids and their parents ____ English, I think. I know it from their accent.
A. is
B. been
C. are
D. was
【单选题】
You had better ___ a doctor as soon as possible.
A. seeing
B. saw
C. see
D. seen
【单选题】
He opened the letter and it contained ___.
A. an important information
B. some important informations
C. many important information
D. some important information
【单选题】
He has been writing for 3 years, but being a writer is not his ___.
A. chance
B. choice
C. change
D. character
【单选题】
They have never heard any ___.
A. a customer complaint
B. the customer's complaints
C. customer's complaint
D. the customers' complaints
【单选题】
He is not a child ___.
A. no more
B. no longer
C. any much
D. any more
【单选题】
The retired man is used to ___ his two dogs early in the morning.
A. exercise
B. exercising
C. exercised
D. exercises
【单选题】
It was not ___ midnight that they discovered the children were not in their bedroom.
A. before
B. at
C. after
D. until
