请教一道题，OG62一个句子两个动词？

透影波心

62. 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) to establish tighter restrictions on the amount of
grain farmers will be allowed to grow and to
encourage
答案是E，可是为什么一个句子有两个动词啊？will be出现两次，谢谢各位牛牛

清飞扬

E中把that省掉了，establish tighter restrictions on the amount of grain (that ) farmers will be allowed to grow，你看意思是不是就对了？

透影波心

哎？还真的，可是什么时候可以省略什么时候不可以省略啊，谢谢你