GWD-9-Q32:

The United States minted about 857 million silver-colored “Susan Anthony” dollars between 1979 and 1981, but the coin proved unpopular because it looked and felt too much like a quarter.

A.      The United States minted about 857 million silver-colored “Susan Anthony” dollars between 1979 and 1981, but the coin

B.       About 857 million silver-colored “Susan Anthony” dollars were minted as coins in the United States between 1979 and 1981 but

C.      About 857 million silver-colored “Susan Anthony” dollars that were minted between 1979 and 1981 in the United States

D.      About 857 million silver-colored “Susan Anthony” dollars that the United States minted between 1979 and 1981

E.       Between 1979 and 1981 the United States minted about 857 million silver-colored “Susan Anthony” dollars, which

请问 A中 proved 前是否应该加was， 变成被动语态？意思为：这个硬币被证明是不流行的，因为。。。。

prove 比较特殊,可以用主动表被动，这儿和become用法一样，可翻译成 be

Longman
2
?BE?
[linking verb] if someone or something proves difficult, helpful, a

problem etc, they are difficult, helpful, a problem etc
The recent revelations may prove embarrassing to the President.
prove to be something
The design proved to be a success.

用主动表被动的动词还有 read like, read well, prove helpful, sell well （摘

自白勇语法）

非常感谢，可是在gmat中有几道题一定是要prove 变成被动才算对。那怎么区别

何时加被动，何时为主动表被动呢?