某工程，甲单独完成需4天，乙单独完成需8天，现甲先工作1天后和乙加入合作，问甲、乙合作几天才能完成这项工程。设甲、乙合做x天才能完成这项工程，列一元一次方程 ___。
题目分析：先根据两人的工作时间表示出两人的工作效率，再根据甲先工作1天后和乙加入合作，即可列出方程.
由题意可列方程为
点评：解答本题的关键是读懂题意，根据两人的工作时间正确表示出两人的工作效率.
| Society can be broken up into three classes: the Elite, the Meek and the Masses. The Elite are (51) of the top 10% of society, those that don’t need anyone’s help (52) tcomes to get ting what they want. They have the status, the money, the power, and the respect to (53) whatever they need．In spite of the fact that they enjoy the upper hand, people outside of this class will still go to great (54) to help them even further. The Meek are comprised of the bottom 10X of society, those who need our help, and badly at that. But (55) so many of us are eager to get in well with the Elite, few actually care enough to provide any (56) to the Meek. The Masses are the largest class, (57) up the middle 80% between the Meek and the Elite. Most of the Masses could use some help getting by, and (58) it would usually improve their lives considerably, but they (59) get it. Why do most people would rather help the Meek or the Elite Because they are (60) with instant gratification or the anticipation of future benefits. We rarely help the Masses because there is nothing really in it for us, and this shows humanity’s true colors. |
A．when
B．whenever
C．if
D．even if