螺栓与螺母紧固时，螺栓尾部伸出螺母平面的长度不得大于（）个螺距。
A、1
B、1.5
C、2
D、2.5
参考答案：B
选择最恰当的词填到横线上。
1. The desk is in the___ _. (A. dining-room B. study)
2. The fridge is in the____ . (A. bathroom B. dining-room)
3. The sofa is in the____ . (A. kitchen B. sitting-room)
4. The pencil box is in the______ . (A. school bag B. bathroom)
5. The bed is in the____ . (A. bedroom B. sitting-room)
什么叫电气设备的隔爆？
