某工程甲单独做50天可以完成，乙单独做75天可以完成。现在两人合作，但途中乙因事离开了几天，最后一共花了40天把这项工程做完，则乙中途离开了( )天。

With population growth in an ever-shortening cycle, it is rather doubtful whether the earth can provide enough food for mankind.翻译 点击查看答案

面对严重的财务问题，（）the company had to lay off some of the workers． 点击查看答案