吹扫换热器时，要坚持吹扫一程，另一程（），防止（）。如果换热器有付线，应先走付线，管

郑女士，25岁。孕40周，初产，宫口开全2小时，胎头棘下2cm，宫缩较前减弱，胎膜已破，胎心 120次/分，产妇一般情况较好。行胎头吸引术

胎头吸引术应何时解除负压

A．胎头未娩出时

B．胎头娩出后

C．胎头即将娩出时

D．胎身娩出时

E．胎身娩出后

Every country has its own culture. Even though each country uses doors，doors may have   different functions and purposes 小题1:___________ lead to cultural differences.

When I first came to America，I noticed that

a public building had two different doors and 小题2:___________ had distinct functions. You have to push the door with the word “PUSH” to go out of the building and to pull the door小题3:_________ the word “PULL” to enter  the building. This was new to me, 小题4:_________ we use the same door in South Korea. For quite a few times I failed 小题5:_________ (go )out of a shopping centre and was embarrassed. The way of using school bus doors was also strange to me. I used to take 小题6:__________ school bus to classes.

The school decided that when the driver opened both the front and back doors，students who 小题7:___________off the bus should get off first，and students who were getting on should get on later.

In South Korea, we do not need to wait for people to get 小题8:_________. One morning, I hurried to the bus, and when the bus doors opened, I 小题9:_____________(conscious) tried to get on the school bus through the front door. All the students around looked at me, I was totally embarrassed, and 小题10:___________ face went red. 

工资指导线包括（）。

A.高线

B.预警线

C.低线

D.基准线

E.下线

在带电作业中，通过传递绳滑车的滑轮，采用（）。

A、铁滑轮；

B、铝滑轮；

C、绝缘滑车；

D、都可以。