Question

5. In our class, when the bell rang and the taacher closed his book, it was a        or everyone to stand up.

A．signal

B．chance

C．mark

D．measure

Answer 1

 A

signal 信号； chance 机会； mark 记号；measure  措施。句中的it 代替“铃响时教师合上书”这件事，而“它”正是大家要起立的“信号”。