题目

—       do you play computer games?    —Once a week.   A. How soon                                B. How often    C. How long                                 D.How much 答案：B  how often用于提问频率。10．如图，正方体ABCD-A1B1C1D1中，E是棱BC的中点，F是侧面BCC1B1上的动点，且A1F∥平面AD1E，则直线A1F与平面BCC1B1所成的角的正切值t构成的集合是（　　）A．{t|${\frac{{2\sqrt{5}}}{5}$≤t≤$\frac{{2\sqrt{3}}}{3}}\right.}$}B．{t|{2≤t≤2$\sqrt{3}}$}C．{t|${\frac{{2\sqrt{5}}}{5}$≤t≤2$\sqrt{3}$}D．{{t|{2≤t≤2$\sqrt{2}}$}