LOC的18NM内水平覆盖范围是跑道中心线两侧各（）。A.10度 B.15度 C.2

全口义齿合适的磨光面外形的作用是（）。

A.有助于恢复面部外形

B.有助于固位

C.有助于发音

D.有助于提高咀嚼效能

E.避免咬舌咬颊

John likes     1   (read) very much. His father has a library and the boy    2    (read) most of the books in it. So he often    3    (borrow) books from the school library. He reads books when he    4    (be) free and does nothing but reading at home on Weekends. Once he even    5   (read) a novel in class because it was very interesting. Of course he couldn’t hear what the teacher    6   (say). So he    7    (fall) behind. The headmaster had a talk with him and told him    8   (not read) novels in class. At last, he realized that he was wrong and said “I’m sorry, I    9    (not do) it again.” And now he reads books after he finishes    10    (do) all his homework..

18．Everyone must have known the death of the waitress, __________?

A．must they

B．mustn’t they

C．haven’t they

D．have they

的“U”型金属框架，其框架平面与桌面平行。其ab部分的电阻为R．框架其它部分

的电阻不计。垂直框架两边放一质量为m、电阻为R的金属棒cd，它们之间的动摩擦因数为，且接触始终良好。cd棒通过不可伸长的细线与一个固定在O点的力的显示器相连，始终处于静止状态。现在让框架由静止开始在水平恒定拉力F的作用下（F是未知数），向右做加速运动，设最大静摩擦力和滑动摩擦力相等。最终框架匀速运动时力的显示器的读数为2mg。已知框架位于竖直向上足够大的匀强磁场中，磁感应强度为B。求：

（1）框架和棒刚开始运动的瞬间，框架的加速度为多大?

（2）框架最后做匀速运动对的速度多大?        

所标明的适应证超出规定范围的药品是（）

A.假药

B.劣药

C.质量不好的合格药品

D.中成药

E.进口药