关于色素增加正确的是（）
A.常见于白癜风
B.常见于白化病
C.常见于黄褐斑
D.常见于无色素痣
E.常见于花斑癣
参考答案：C
开发利用水资源，应当首先满足的是下列哪一选项内容( )。
A．农业用水
B．工业用水
C．航运需要
D．居民生活用水
— Did you go to the open-air concert?
— No. We ____. but we spent too much time shopping. [ ]
A. could have gone
B. must have gone
C. can't have gone
D. shouldn't have gone
