let in: 让…进入、放…进来
A braver step would be to let in foreign operators to boost competition.
更大胆的举措便是让外国同行进入中国市场以提升航空业的竞争水平。
China let in the foreign carmakers, but on condition that they worked with local partners.
中国则允许外国汽车制造商进入，但条件是他们必须与本国汽车制造商合伙经营。

work out: 解决、找到答案
I just have that confidence that things are going to work out fine.
我就是有信心，相信事情总是能解决得很好。
What is not easy to work out is exactly how many photons have arrived.
比较困难的问题是，精确的计算出到底有多少光子到达。

by now: 至此、到如今
By now the desk should be looking significantly tidier!
现在桌子看起来整洁多了。
By now I own some forty copies of the magazine.
到目前为止，我拥有大约40本《假日》杂志。