实验室里取8mL水并进行加热，下列需用的化学仪器组合正确的是（　　）

①带铁夹的铁架台；②10mL量筒；③100mL量筒；④酒精灯；⑤石棉网；⑥试管；⑦试管夹；⑧胶头滴管．

A．②④⑥⑦

B．①③④⑥⑧

C．①②④⑥⑧

D．①②④⑤⑥

I____ asleep because it took me a long time to realize that the telephone was ringing.

A．could have fallen

B．should have fallen

C．must have fallen

D．mustn’t have fallen