so it is often difficult to tell whether they are boys or girls.中的difficult to tell whether是什么
问题描述:
so it is often difficult to tell whether they are boys or girls.中的difficult to tell whether是什么
答
so,连词,“所以”.
it is often difficult 是主句,it 作形式主语,
to tell whether they are boys or girls 动词不定式作真正的主语,而 tell 后面的 whether 引导一个宾语从句.
原句中文意思:所以经常难以判断他们是男孩还是女孩.