Question

This problem is too difficult for us to ____

A. to work ot out
B. to work out
选哪个啊？为什么呢？解释一下 谢谢

Answer 1

B正确，主语this problem在意义上是work out 的宾语，因此后面的it就没必要带了

Answer 2

选B this problem 作 to work out 的宾语

Answer 3

选B too+adj/adv to+v（原型）A项 是个表语从句了故不选。

Answer 4

b