肾糖阈
参考答案：
肾糖阈指尿中不出现葡萄糖的最高血糖浓度。
有一汽车沿着坡度为3：4的斜坡向下走了1000米，则它距离地面的垂直高度下降了______ 米．
Do you think the problem is ______? If you think hard, you'll find it ______ to work out. [ ]
A. hard; easy
B. easy; hard
C. hardly; easily
D. hard; easily
