you should b-- a present for Allen on his birthday.填bought还是buy?句中能看出是过去时态吗?如果是将来时态就应该是you should buy a present for Allen for his birthday.风唱梵音
问题描述：
you should b-- a present for Allen on his birthday.
填bought还是buy?句中能看出是过去时态吗?
如果是将来时态就应该是you should buy a present for Allen for his birthday.
风唱梵音
答
可用should have bought,表示你本应该.....是过去，若是将来用buy 可以
答
答案是you should buy a present for Allen for his birthday
因为句中有（should 应该）就是还没过去的意思
答
buy也可以,have bought 也可以.
buy 的话意为 你应该为Allen买个生日礼物.（将来时）
have bought 的话意为 你本应该为Allen买个生日礼物的.（实际上没买）（过去虚拟时）