until 和before 有区别吗
问题描述：
until 和before 有区别吗
题:this book was so interesting that he read it for three hours ____ he realized it.
a.when b.until c.after d.before
答
选择B ：until
before只是陈述以前的事实,用until则着重后来的变化情况.
阅读在理解前面,而realized是阅读的结果.