如下图给出的四个对应关系,其中构成映射的是( ) A.(1)(2) B.(1)(4) C.(1)(2)(4) D.(3)(4) 答案:B 解析:在(2)中,元素1和4没有对应元素;(3)中元素1和2都有两个元素与它们对应,不满足映射的定义;(1)、(4)符合映射定义.故选B.-- Where do you plan to go this summer holiday?--I plan a _________visit to Xiamen.A. three-days B. three-day C. three days