求语法解析!he seems to be studying it .这句中的to be studying为什么这么用,我知道有seem to do sth,这里的为什么用be doing 它在句中做什么成份?这句和he seems to study it有什么区别?

求语法解析!he seems to be studying it .这句中的to be studying为什么这么用,我知道有seem to do sth,这里的为什么用be doing 它在句中做什么成份?这句和he seems to study it有什么区别? he seems to be sick为什么要加to be? He seems (to be) very sad.他看起来很伤心.有to be 和没有,在语法上有什么区别? he seems to be very busy.是不是主系表结构 He seems to be a teacher 同义句 He seems to be a teacherd的同义句 he seems to worried, there seems to be He seems to be worrying about it.He seemed to be worrying about it.两句都对吗? 英语翻译seems possible that he will wim the match.请问：He seems to be able to win this game. He always seems ____ .A.to be quite happier.B.quite happy.C .to be quite. D.that to be happy. 选择解析(ABCD）正确答案是B.小弟感激不尽! He seems to be a teatherSo he is.还是So he does? 英语句中,He seems to be happy with me 句中,to be What seems to be the problem?求句子结构分析 he seems unable to understand you ,he seems unable to understand you ,be unable to do sth的be在哪,seems 前后有漏什么吗,seems 后是加什么的, he seems to be a doctor同义句it( )( )he( )a doctor He seems to be a doctor.(改同义句）It --- ---- he --- a doctor. he seems to be angry with the girlIt ___ ___ he is angry with the girl