an expert on losing

an expert on losing an expert on和be expert in的区别 是be an expert in/at/on ,还是be expert in/at/on? an expert in/on/at有什么区别 an expert in/at/on/with有什么区别?例子：1.an expert in/at teaching small children意思就是说an expert in和an expert at通用对吗?2.an expert in economics3.an expert on foreign affairs4.an expert with the needles he considers himself an expert on the subject 我认为是 he considers himself is an expert on the subject 我是按照中文翻译的就是这样?语法新手. He considers himself an expert on the subject,in fact,he is poor on it.怎么译 Berkeley是哪?Professor Harley Shaiken is an expert on unions at the University of California at Berkeley. I wanna be an expert on English,how I can do this?Is there anybody who can help meon this? I am still ________ on the finances of the league and I'm not going to pretend to be.A.no expert B.not an expert C.not expert D.none expert请解释下为什么选AB不是更完整吗? expert at/on/in 有什么区别 一个英语选择题求指教If I may say,I'm an expert at matching hairstyles _______ personalities.A.in B.on C.at D.to 请问为什么? losing Soon he becomes dependent on the expert.这里的expert怎么翻译? expert用法expert后面带介词in,at,on,有什么区别啊? 请帮忙翻译：He is an expert in sign language. sales.he is an expert and maketing英文翻译 a specialist or an expert in genetics（a noun）