to do & to be donethere's a lot of work to do there's a lot of work to be done这两种说法都对吗?还有为什么说the museum is said to have been destroyed in a big fire five years ago.而不说the museum is said to be destroyed in a big fire five years ago.原句不应该是the museum was destroyed in a big fire five years ago.

这两种说法均可，只不过逻辑主语不一致，
to do 表示逻辑主语是我，我有很多工作要做
to be done 表示主语是别人或我们大家，
当to do 不定式的动作发生在主句动作之前应该用完成时态
the museum is said to have been destroyed in a big fire five years ago.
the museum was said to be destroyed in a big fire five years ago.
这两种说法都对。

there's a lot of work to do 这句是对的。这里必须是主动
the museum is said to have been destroyed in a big fire five years ago中
to have been destroyed 是不定式完成式，表示着动作发生在谓语动作之前。

1.to do一定是自己做to be done是给别人做【I have some work to do】我有些工作要做(工作是我本人来做)【Secretary:Sir,do you want these books to be thrown?】先生,你希望把这些书丢掉吗?（作为秘书,丢书的就是...