明清时期,中国科技没有走向近代化的根本原因是[ ]
A.文化专制阻碍科技和思想的自由发展
B.闭关锁国的对外政策
C.资本主义萌芽发展缓慢
D.自然经济一直占统治地位
答案:D
给算式460÷23-19×60加上括号,使它先算减法、最后算除法的算式是______.
“It’s a long time since I enjoyed myself.” This sentence means______.
A.I enjoyed myself for a long time
B.I haven’t enjoyed myself for a long time
C.I want to enjoy myself
D.What a long time after I enjoyed myself