水中少量硫酸盐对人体无影响，但过量时有致泻作用，饮用水中硫酸盐的含量不应超过（）mg／L。
参考答案：250
It is reported that the oil reserves in this region are richer than ________ in other places.[ ]
A. one
B. that
C. those
D. ones
