标志着中国新民主主义革命伟大开端的五四运动，有其发生的历史必然性，下列论述正确的是

①辛亥革命没有完成反帝反封建任务

②封建军阀割据混战

③无产阶级队伍壮大

④思想解放潮流促进了中国人民的觉悟

A.①②③                B.②③④

C.①②③④              D①④

When I saw his pale face, I ________ what ________. [ ]

A. realized, had happened

B. was realizing, was happening

C. realized, has happened

D. has realized, had happened