■若在其中的形容词be为如今式（am, is, are），则之后不定式一般只有是静态动词，不可以是动态性形容词。如：

They are fortunate to be able to buy such a large a house.她们真好运，能买那般大的房屋。

但不能说：They are fortunate to buy such a large house.

■若想在am[is, are]fortunate后接动态性形容词，则要用进行式或进行式。如：

They are fortunate to have bought such a large house.她们很好运，买来那般大的房屋。

You are fortunate to be working in London.你简直好运，能在纽约工作中。

■若在其中的形容词be为过去时（was, were），则之后不定式便沒有之上限定。如：

He was extremely fortunate to escape without injury.他能安然无事地逃离，实在太好运了。

He was fortunate to have had the chance of doing so.他很好运还有机会那样做。

■be fortunate后接不定式与接从句含意稍有不一样：It is fortunate that…的意思是“……是件好事儿”，而“主语 befortunate to do sth”则注重主语的好运。如：

It’s fortunate for us that he has a rich uncle他有一位富有的大伯是大家的运势。（如能够替大家借款）

He’s fortunate to have a rich uncle.他真好运有一位富有的大伯。（很多人沒有）