It worried the mother a lot _______ she couldn't afford the medical treatment for her son.这个是什么从句?用什么引导词?为什么?
问题描述：
It worried the mother a lot _______ she couldn't afford the medical treatment for her son.
这个是什么从句?用什么引导词?为什么?
答
how
是主语从句
如何给儿子支付治疗费用让妈妈很担心
答
这是个主语从句.划线的地方填 that .it 在句中作形式主语,而that 作为真正的主语后置.出现这种情况,是因为真正的主语过长,为了避免头重脚轻的现象,所以用it 做了形式主语.
it worried the mother a lot that she couldn't afford the medical treatment for her son.
可以= That she couldn't afford the medical treatment for her son worried the mother a lot.