When you are using gas, that one of the windows is open.A.be sureB.make sureC.ch
来源：网络
时间：
推荐文章
When you are using gas, ________ that one of the windows is open.
A.be sure
B.make sure
C.check
D.B or C
试题答案
D
题意：当你使用煤气时，要确保开着一扇窗子。make sure that..., check that...都可表示“确保……”。be sure that“确信……”，不符合题意。