Question

15．The little boy is so weak that he can't lift the heavy box．（改为简单句）
The little boy istooweaktolift the heavy box．

Answer 1

分析 小男孩是如此的弱小以至于他不能举起这个重箱子．
小男孩太弱小了举不起这个重箱子．

解答 答案：too，to．原句中的so…that表示如此…以至于，结合下面的weak是形容词"弱小的"，lift是动词原形"举起"，故用too+adj/adv+to do sth太…而不能做某事，来互换，故答案是too，to．

点评 too…to（太．而不能）
so…that（如此．以至于）
adj enough to…（ 足够…去做某事）三者之间可以互换she is too young to go to school=she is not old enough to go to school=she is so young young that she can not go to school