Tom should have come by now.
问题描述：
Tom should have come by now.
答
Tom should have come by now.
Tom到现在本该来了。[实际上还没有来。]
should have done sth.本该做某事（却未做） (并带有责备语气)
ought have done表示本应该做但事实上还没做,但不带有责备语气~
答
tom现在应该已经来了..
答
Tom 应该早就到了
答
Tom早应该到了;
答
Tom should have come by now.
Tom到现在本该来了.[实际上还没有来.]
should have done sth.本该做某事（却未做）
by now到如今,到现在
答
TOM应该已经过来(现在完成时...好象有点翻译不准..)
答
汤姆现在本该来了
should have done 表示本来应该怎么样