圆x2+y2=4与直线l:y=a相切,则a等于( )
A.2
B.2或-2
C.-2
D.4
要直线直线与圆相切,需圆心到直线的距离为半径,
即|a|1=2
∴a±2
故选B
The teacher insisted that I ____ a mistake and insisted that I ____ the physics problem again.
A.made; did
B.made; do
C.make; do
D.make; did
欲显示或隐藏“资源管理器”窗口中的“地址栏”,应使用()菜单。
A.“文件”
B.“编辑”
C.“查看”
D.“工具”