题目

 Parents who look to having a second child are facing a dilemma. This is ________many of them have passed their golden age.    A. why             B. how              C. because            D. whether 答案：C珠穆朗玛峰最高处海拔8844米，吐鲁番盆地低于海平面154米，两地的相对高度为（ ）A、8694米 B、8998米 C、10000米 D、8000米