一道中译英题目：从他的反应来看，他似乎已经完全忘记了之前的承诺，这让我们实在想不通。（appear）

Judging from his reactin, he appeared to have forgotten his previous promise......

这里为什么不能写成he appeared having forgotten呢?

解答如下：

appear 为系动词用法，后面可以接，“名词，形容词，介词短语，不定式，过去分词，”但是不能接动名词doing。

(1)appear to do sth 好像要去做某事（不定式与appear动作同时或者之后发生）

He appears to tell me something.

他好像要告诉我一些事情。

He appeared to be talking to himself.
他似乎是在自言自语。

They appeared to be avoiding him.
他们像是在躲着他。

She appeared not to notice anything.
她似乎没看见什么。

(2)appear to have done sth 似乎已经做了某事（不定式动作在appear之前发生）

The aircraft appears to have crashed near Katmandu.

飞机似乎在加德满都附近坠毁了。

You appear to have travelled a lot.
看来你到过不少地方。

She appeared not to have heard what he had said.
她似乎没有听见他的话。

备注：appear 还可以接以下几种搭配

(1)it appears that

It appears that some missiles have been moved.

一些导弹似乎已经被移走了。

It appears unlikely that the UN would consider making such a move.

看起来联合国不太可能考虑采取这样一种行动。

(2)appear +名词

The presidency is beginning to appear a political irrelevance.

总统一职似乎正在沦为政治上的摆设。

(3)appear+形容词

Nine months later, those talks appear as distant as ever.

9个月以后，那些会谈似乎仍然遥遥无期。

He appeared willing to reach an agreement.

他似乎愿意达成协议。

(4)appear+介词短语

The aeroplane appeared as a small speck in the sky.
那架飞机在高空像个小黑点。

From the air, the city appears as one stretch after another of dense greens with buildings set among them.
从飞机上看,这座城市像是一片接一片葱郁的树林,一幢幢楼房点缀其中。

He tried to appear at his ease.
他装出安详的样子。

(5)appear+（分词）形容词

He appeared taken aback.
他显得很吃惊。

He appeared perplexed.
他显得迷惑不解。

They appeared amused by the story.
他们听了这故事显得很高兴的样子。

(6)appear to sb as if

It appears to me as if he will win.
据我看,他好像能赢。

It appeared to me as if she was ill.
依我看她似乎生病了。

(7)it appear+adj. (for sb) to do 

It appeared unlikely for them to arrive on time.
看来他们不太可能准时到达了。

It appears reasonable to give him a three-day leave.
给他三天假,似乎也合理。

(8)It appear adj./n.+that从句

It appears  very unnatural that he should speak on her behalf.
他既然代表她讲话,看来这是很反常的。

It appears unlikely that he will take the position.
看来他不太可能就任这个职务。

It appears a blunder that he should have used that word.
他既然使用这个字眼,看来是个大错。

   （1）reactin 应该改为 reaction

   （2）appear 后面可以接动词不定式，不能接动名词。所以，这里的 he appeared 

to have forgotten 不能写成 he appeared having forgotten。