1 If you blood ____badly,your hands and feet will get cold e

1 If you blood ____badly,your hands and feet will get cold easily.A passes B crosses C circulates D circles这几个次有什么区别啊2 The progessor referred to ___yesterday.A come B came C　ｃｏｍｉｎｇ　　Ｄ　comes这个又为什么选B呢 不是doing吗3 He insisted that he ____frome hesrt trouble,but I didn't think so,A should suffer B has suffered C suffers D was suffering这个为什么选D呢 这个是关于什么的语法?