选哪个,怎么回事,请懂的帮忙下

选B
as .as...像...一样
as .as...像...一样
两者之间的词可以是副词也可以是形容词,要根据所修饰的部分确定.
在意思上它们是一样的,但用法不一样,在否定句中既可以用not as ...as...也可以用not so...as,而在肯定句中只能用as...as.．．
He is as clever as you He is not as/so clever as you.
本例中修饰speak(动词）用fluently 副词 排除C
而本句也是肯定句,故只能用as ...as...所以选择B
意思是我们美国老师说法语和说英语一样流利