问题补充:
. In our class, when the bell rang and the teacher closed his book, it was afor everyone to stand up.
A. mark
B. chance
C. signal
D. measure
答案:
A. mark
B. chance
(答案→)C. signal
D. measure
解析:词义辨析。mark标志,符号;chance机会,运气;signal信号,暗号;measure测量;尺寸。句意:在我们班的,当铃声响时,老师合上他的书,这对于每个人来说是一个起立的信号。故选C。