母乳中含有促进婴儿脑发育的重要物质，包括
A．鞘磷脂
B．卵磷脂
C．必需氨基酸
D．乳糖
E．牛磺酸
参考答案：B, C, D, E
I___there little more than a week when I set to work with the scientist.
A．would be
B．have been
C．had been
D．will be
炉窑砌筑修砖时，砍砖的厚度不得超过原砖厚的（）以上。
A.1/4
B.1/3
C.1/2
D.2/5
