It is as if a single unimportant event set up a chain of rea

表语从句啊It is+表语（所谓的主+系+表） 表语用as if引导,翻译出来就是：好像是一件无关紧要的小事引起了一连串的连锁反应举几个例子吧She looks as if she were ten years younger．她看起来好像年轻了十岁。It seems as if our team is going to win．看来我们队要胜了。It looks as if a tornado swept through your room。好像有龙卷风席卷过你的房间。It looks as if they're looking for something。他们看起来好像在找什么东西。