枕外隆凸的内面是()
A.上矢状窦
B.下矢状窦
C.直窦
D.窦汇
E.乙状窦
参考答案:D
区别棉花和羊毛的最简单的方法是( )
A.加入稀硫酸后加热使之水解,检验水解产物能否与新制Cu(OH)2反应
B.浸入浓硝酸后,观察其颜色是否变黄色
C.在火中灼热,闻其是否有烧焦羽毛的气味
D.通过化学方法测其组成中是否含有硫、氮等元素
I don't think he tried his best to learn English, ______? [ ]
A. did he
B. do I
C. didn't he
D. don't I