路灯控制不当或建筑工地的聚光灯,照进住宅,影响居民休息,是一种( )。
A.视觉污染 B.灯光污染C.不可见光污染 D.电磁波辐射污染
参考答案:B
设x2-xy+y2=1(x,y∈R),则x2+y2的取值范围为( )。
Excuse me, Marcia, a reporter from Vanity Fair _____ all day. Could you speak to her now? [ ]
A. phones
B. has phoned
C. has been phoning
D. phoned