1)I thought he was out of his mind. out of one's mind 疯了,晕了头了
例句 What do you mean you’re dropping out of school to join a rock band?Are you out of your mind?
2)A little bell didn’t go off in your head/mind . a little bell goes off in your mind突然想起一件很重要的事
例句 How could you forget to watch Action English. That's our program.Didn't a bell go off in your mind to remind you?
3)I don't even know who you are anymore. 我都不知道你是谁了；我都快不认识你了。
例句 First you told me you're from America,and then you said you're from Canada. Now I find out you're from Australia.I don't even know who you are anymore.