答案:D
已知圆的半径为2,圆心在x轴的正半轴上,且圆与直线3x+4y+4=0相切,则圆的标准方程是 ______.
Peter ________ under the pressure of his position and was unable to work for a year.[ ]
A.settled down
B.broke down
C.passed away
D.broke out