帮忙写出下列词或词组的复数形式

问题描述:

帮忙写出下列词或词组的复数形式
book、box、orange、baby、boy、this、that、knife、watch、sheep、tooth、leaf、German、Chinese、woman doctor

books,boxes,oranges,babies,boys,these,those,knives,watches,sheep,teeth,leaves,Germans,Chinese,women doctors