地面能见度
参考答案：视力正常的人在地面向水平方向能看清最远目标物轮廓的距离。
Don't be__________by products promising to make you lose weight quickly. [ ]
A. taken off
B. taken out
C. taken away
D. taken in
在最坏情况下，堆排序需要比较的次数为______。
