— What country is this?
— It's _____________. [ ]
A. London
B. China
C. Washington, D. C.
答案:B
求经过两圆x2 + y2 + 6x-4 = 0和x2 + y2 + 6y-28 = 0的交点,并且圆心在直线x-y-4= 0上的圆的方程。(8分)
We must __________ a topic before we start to write. [ ]
A. decide between
B. decide to
C. decide on
D. decide against