Do drop in whenever------ a.you are convenient.b.it is convenient to you 为啥a不对?

Do drop in whenever------ a.you are convenient.b.it is convenient to you 为啥a不对? just drop in whenever you feel like it翻译 翻译：Drop by whenever you are in the area ( )【drop by】 whenever you're in this area drop ___us whenever possiblea on in b on with c in on d in for 关于drop in的用法drop in 有drop in to do sth吗eg:Drop in to see us any time.improper to drop in on him so casually.drop in on sb drop by 怎么用 -----Do ____me when you come to America next time .-----Sure,I will.A.drop B.drop in C.drop in at D.drop in on drop-in 和drop out It is my sincere hope that we could have more exchanges in the future and drop in us whenever you are in this part of the world.这句话中drop in us whenever you are 还是whenever you were?说明原因,不用翻译,我就想问问时态 drop in与drop by的区别 英语翻译drop offdrop in drop downdropping off drop in和drop by的区别 drop in和 drop by 的区别 drop by,drop in的区别? DROP IN ON drop in什么意思? drop in on drop-in-replacement是什么意思