this picture is believed 填空 painted by Turner A it was B to

一个固定的句型：主语+be done + to do;意为：“据。主语,”如：The boy is said to be honest。这孩子据说很诚实。这里用的是不定式的一般式,表明动作发生现在或与谓语同时发生。如果不定式的动作发生在谓语动作之前,就要用它的完成式,即：to have done。The picture is believed to have been painted by Turner。画是被画的,所以用了被动式。而且动作发生在谓语之前,所以用了完成式。即不定式的完成被动式。