根据赞可夫的研究认为;“一般发展”以( )为核心。
A.知识
B.能力
C.情感
D.智力
参考答案:D
按GB7588-2003《电梯制造与安装安全规范》规定,机房必须安装永久性人工照明,光照度应不小于()lx。
A.50
B.100
C.150
D.200
By the time you ____ in, I ____ two letters.
A.had come, had written
B.came, wrote
C.come, have written
D.came, had written