库克曲线表明,创造力较强的时期大约有()年
A.1.5
B.2
C.4
D.3
参考答案:B
解析:库克曲线表明,创造力较强的时期大约有4年。参见教材P229
24. —Mr Smith, ______ John ______ this week? A friend of his is coming to see him this afternoon.
—No. He is on holiday.
A.has; worked
B.is; working
C.did; work
D.does; work
产品需求通常指针对特定产品的欲望即对某一产品或服务的“市场需求”,它是建立在()条件之上的。
A.有支付能力
B.有购买行动
C.愿意购买
D.实际购买