如有电线电器起火，应（）
A.切断电源
B.用沙覆盖
C.可用二氧化碳灭火器
D.可用泡沫灭火器
参考答案：A, B, C
It is difficult _______ the book in one day. It is so thick. [ ]
A. to finish to read
B. to finish reading
C. finishing reading
D. finishing to read
计算题：悬臂胶带总长78m，运行速度为2m/s，试问胶带机运转一周需要多长时间？
