问题
选择题
Experts are trying to work out a plan to deal with the problems caused by global warming _________ it is too late.
A．if
B．before
C．when
D．until
答案
答案：B
考查连词用法。Before在…之前；在不同句子中的翻译比较灵活。句意：专家正在努力的制定一个在情况变得严重之前来处理由全球变暖导致的问题的计划。