工人用如图甲所示的滑轮组运送建材上楼，每次运送量不定。滑轮组的机械效率随建材重力变化的图像如图乙所示，滑轮和钢绳的摩擦力及绳重忽略不计，g取10N／kg。
The introduction of the story book
Name
EmmaandJerry
For whom
It's especially suitable for .
Contents (内容)
It has 10 short stories, and they are .
The exercises include vocabulary, and writing.
There is a to match each story.
Pages & Price
It has pages and costs 9.9 dollars.
已知x-2y=-2,则3-x+2y的值是（ ）
个人利益与公共利益彼此依赖，相互包容。作为社会中的一员我们应该（ ）①学会正确处理公共利益与个人利益的关系 ②在优先保证公共利益的前提下，促进个人利益充分实现③不管在任何时候都不能考虑个人利益 ④在公共利益与个人利益冲突面前优先考虑个人利益
