XDF 123-7

18.   Even though the state has spent ten years and seven million dollars planning a reservoir along the Ubi River, the project will have to be abandoned as a result of the river becoming so heavily polluted.

(A) will have to be abandoned as a result of the river becoming so heavily polluted

(B) is to be abandoned on account of the heavy pollution which the river received

(C) had to be abandoned because the river had received such heavy pollution

(D) has to be abandoned because of the river and its heavy pollution（E）

(E) must be abandoned because the river has become so heavily polluted

答案:E   must     , have to 可以互换?

不选择d选择e不单是用must代替has to.

because of the river and its heavy pollution将原句的意思给改变了。

原句的意思是because of  heavy pollution of the river