Are these boys your friend?中friend要写成复数形式吗?超级急快怏怏

Are these boys your friend?中friend要写成复数形式吗?超级急快怏怏 this your friend?(改为复数形式) 问题二Are these your books?(改为单数形式) ' Are these your friend哪里错了 自学英语问题This is my friend.用复数形式改写这个句子,后变为:These are our friend Is she your friend的复数形式 Is this your friend?改为复数形式 These are my friend my friend 复数形式 Is she your friend?写出下列句子的复数形式 Are these your friend?A.Yes,these are B.No,they are C.Yes,th your are my friend. girl friend的复数形式