Wehavefriendstohelpusfightagainstpollution,andtreesare...

問題詳情：

 We have friends to help us fight against pollution, and trees are one of ________.

A. themselves                                        B. they

C. their                                                   D. them

【回答】

D

知識點：人稱代詞

題型：選擇題