1.The soon realized that,

网友回答

1.deal with与situation之间是被动的关系,省略主语的同时省略谓语,即补全后
They soon realized that unless (it was) carefully dealt with,...
2.last也有延续之意,但不可以做系动词,直接接形容词作表语,而stay可以
======以下答案可供参考======
供参考答案1:
1.The soon realized that,____,the situation would get worse.
A unless dealing with carefully
B if not carefully dealing with
C unless carefully dealt with
D if dealt not carefully with
答案是C WHY
unless=if not
如果不小心处理的话,情况会更糟的
2．It is said that the weather will____hot for another three or four days.
A last B stay
答案B WHY
stay持续