Question

() 4. (2015 •永州) is very dangerous to swim alone in the river.

   A. It   B. This   C. That

Answer 1

4. A

4. A (考查代词用法。句意:独自在河里游泳是非常危险的。it 是形式主语，动词不定式to swim alone in the river是真正的 主语。)