题目

河姆渡、半坡、大汶口三处遗址的共同点是①种植庄稼 ②饲养生畜 ③制作陶器 ④建造房屋居住A．①③④B．①②④C．①②③D．①②③④   答案：D解析:略  It was the third time that this question _______ at the meeting.    A. had come up       B. was come up        C. has come up       D. is come up