⑴I'm listening to music ____           A. but the teacher comes.

⑵Lucy is playing with her dog,____    B. but my friends come to play with me.

⑶The pupils are talking very loudly,____     C. but her mother calls her.

⑷A bus is coming,____                 D. but it starts to rain.

⑸We are having a picnic,____       E. but there are too many people on the bus.

It____Alice half an hour____ ____at the station．

①干冰可用于钠、镁等金属的灭火

②用稀硝酸和亚硫酸钠制备二氧化硫

③制取二氧化碳时没有检查装置的气密性

④将水沿烧杯内壁缓缓加入浓硫酸中，用玻璃棒不断搅拌

⑤用酒精代替苯从溴水中萃取出溴

⑥夜间厨房发生煤气泄漏时，应立即开灯检查煤气泄漏的原因，然后打开所有的门窗通风．