瓦斯积聚是指瓦斯浓度在2%以上，体积达到（）m3。
A、0.5
B、1
C、1.5
参考答案：A
选择与句中划线部分意思相同或相近的词或短语。
The old man had to stop his work because of his poor health. [ ]
A. give up
B. put up
C. look up
D. turn up
Try to _______ him to let us go with him.
A．manage
B．suggest
C．persuade
D．allow
