he considers himself an expert on the subject

He considers himself an expert on the subject,in fact,he is an expert on losing 英语语法：By no means does he regarded himself as an expert,altho Soon he becomes dependent on the expert.这里的expert怎么翻译? He is an expert on computer .When it comes to computer ,he _ an expert on和be expert in的区别 改为否定句：he taught himself on the Internet he（ ）himself on the The old man is an expert. He can r______ all kinds of machin He showed himself surprisingly________(knowledge)on the subj He always considers the interest of all people on the subject 是be an expert in/at/on ,还是be expert in/at/on?