北美洲原油储量最丰富的国家是哪个国家？
参考答案：加拿大
-Excuse me,have you got a light?
-______ I don't smoke. [ ]
A. Don't mention it
B. Never mind
C. I'm afraid not
D. Thanks a lot
下列表达式中正确的是
A．5++
B．(a+b)++
C．++(a+b)
D．++x
