设f（x）为连续函数，（）。
参考答案：1
解析：
—Bad luck! It’s too late.
—It doesn’t matter. The concert for only a few minutes. You can’t miss it.
A．has begun
B．has been on
C．began
D．lasted
—How many years has life been on earth?
— years, I think.[ ]
A. 5 millions
B. 5 millions of
C. Million of
D. Millions of
（）。
（）。