Helen doesn't look _____ today. Is she ill? [ ]
A. better
B. well
C. nervous
D. happy
答案:B
在矩形ABCD中,AB=5,BC=12,⊙A的半径为2,若以C为圆心作一个圆,使⊙C与⊙A相切,那么⊙C的半径为 。
机动车在雾天临时停车时,应开启什么灯
A.危险报警闪光灯、示廓灯和后位灯
B.左转向灯、示廓灯和后位灯
C.前大灯、示廓灯和后位灯
D.倒车灯、示廓灯和后位灯