过去分词和现在分词完成被动式的区别：

It is said that Beijing University was the first institute of higher learning___ in China.

A. established B. being established C. to be established. D .having been established.

据说北大是中国第一家高等教育学府。

修饰institute，作定语，选择过去分词，表示被动和已经完成。

B现在分词被动式，表示被动，但表示动作正在进行

C不定式被动式，表示被动，但表示动词将要进行

D现在分词完成被动式，表示被动，也表示动作已经完成，但不能做定语,所以选择A

过去分词和现在分词完成被动式的区别：

及物动词的过去分词没有完成式，但它有“完成”的含义，所以它可以代替现在分词完成被动式。

eg:The bridge had been weakened by successive storms and was no longer safe .=

Weakened by successive storms,the bridge was no longer safe.=

Having been weakened by successive storms,the bridge was no longer safe.=

这座桥接二连三地遭到暴风雨的袭击后，己经不安全了。

但若强调分词表示的行为发生在后一个动词表示的行为之前时，可用现在分词完成被动式。

eg:Having been warned about the bandits,he left his valuables at home。

当警告有强盗出没时，他就把贵重物品留在家里。

通常过去分词可作定语使用，而现在分词完成被动式却不能用作定语。

eg:The computer centre,opened last year,is very popular among the students in this school.(MET 93)

去年开办的计算机中心很受学生的欢迎。　　(过去分词既能表示被动又有完成的含义)

The first textbooks written for teaching English as a foreign language came out in the 16th century.(NMET　94)

作为外语的英语教科书早在十六世纪就已经出版了。

Most of the artists invited to the party were from south America(MET 90)

应邀参加舞会的大多数艺术家都来自南美。