“sb's been doing sth ”怎么理解 这个“'s”是is 还是was

“sb's been doing sth ”怎么理解 这个“'s”是is 还是was let's sb to do sth还是doing sth mind sb doing sth与mind sb‘s doing sth相同吗? 想像某人做某事是“imagine sb doing sth”还是“imagine sb‘s’ doing sth”? mind sb doing sth和mind sb's doing sth都对吗?有哪些词可用sb' doing help sb doing sth sb doing sth是什么意思? stop sb doing sth suggest sb doing sth sb spend + doing sth sb was doing sth mind one's doing sth=mind sb to do sth=mind sb doing sth?它们相等吗? fancy sb's doing sth与fancy sb diong sth要怎么区别? it's time for sb doing sth滴造句 imagine sb 或one's doing sth英语造句 have been doing sth 到底是approve of sb's doing sth还是 approve of sb doing sth?这两者有区别吗 warn sb.against (doing)sth.