og11-54

20.   When Congress reconvenes, some newly elected members from rural states will try and establish tighter restrictions for the amount of grain farmers are to be allowed to grow and to encourage more aggressive sales of United States farm products overseas.

(A) and establish tighter restrictions for the amount of grain farmers are to be allowed to grow and to encourage

(B) and establish tighter restrictions on the amount of grain able to be grown by farmers and encouraging

(C) establishing tighter restrictions for the amount of grain farmers are allowed to grow and to encourage

(D) to establish tighter restrictions on the amount of grain capable of being grown by farmers and encouraging（E

(E) to establish tighter restrictions on the amount of grain farmers will be allowed to grow and to encourage

这道题选出E，没有什么疑问，但是在看og的解释时，说and to encourage 和to establish是并列的，所以是两个不定式的并列。

小弟的问题是：如果encourage前面的to省略掉的话，是不是也是正确的？ 不定式并列时，to是可以省略的吧？