一道超级费解的题目~~~求救~~~

Piaget’s research revealed that children can learn to count long before the recognition that a pint of water poured from a small glass into a large one remains the same amount of water.

a.      the recognition that

b.       they can recognize that

c.       they would recognize

d.       they could have the recognition of

e.       having the recognition of

答案B

为什么主句过去时，从句却用现在时？？？

A有什么错误？？？before 用做介词后面不是应该接名词吗？B 接句子，这样的语法结构可以吗？

选B，是想强调与前面的children can learn并列吗？若是并列，哪个词表示这是一个并列句？？？

这其实就是一个比较结构，前面是children can learn, 所以后面就是children can recognize

好专业哦~~~感谢~~~