it isn't convenient for me to move around,so i'd like to have my reference book___my research.A.within B.under 这两个选哪个?固定用法么?

no,it isn't isn't it nice say it isn`t 英语翻译Isn't it dangetous a isn't ball it isn' t it怎么读 Isn’t it a something? Say It isnt Sohsgsgssg “say it isn't so” Isn't it great翻译 I know it isn’t isn't it?是什么意思啊 Small world ,isn't it It isn't a find day,isn't?中有没有错 isn't there和isn't it的区别 but it is impossible isn't it? it isn't =it's not It's not = It isn't