幫我做一下英文句型分析?

comprise是及物動詞（有主動及被動的變化）：
The United States comprises fifty states.
The committee is comprised of eight members.

The European Union is an economic and political federation comprising 25 countries.
= The European Union is an economic and political federation which comprises 25 countries.
修飾語可用分詞片語comprising 25 countries（現在分詞表示主動：包含xxx）或形容詞子句which comprises 25 countries.

The European Union is an economic and political federation comprised of 25 countries.
= The European Union is an economic and political federation which is comprised of 25 countries.
用過去分詞（表示被動：由xxx所組成的），這也是正確的寫法。simple sentence vs complex sentence

你給的句子錯誤。因為主要動詞是is，主詞補語federation的後面不能用再用一個動詞comprise。

In this pattern the object is a gerund.
eg:-Subject+vt----The E.Union is;
------gerund:--------comprising (of 25 countries)-----the gerund is equivalent to a passive infinitive=to be comprised of;"comprise vt"=be composed of; have as parts,members of the committee.NB.comprising of.