at the back of: 在…后面
More importantly, she never again stood at the back of the line.
更为重要的是，她再也不躲在队列的末尾了。
We may detect at the back of it a characteristically british reluctance to regard any one system as the best of all.
我们可以发现在其背后，英国人典型地不愿将之视为最好的一种制度。

pass by sb: 从某人身边经过
Write this promise out on a piece of paper and post it somewhere that you pass by every day.
将这一承诺写在一张纸上，将它贴在你每天要经过的地方。
People that pass by the area will see your name on the sign announcing your sponsorship.
路过的人们会看到宣布你认领的标志上你的名字。

at one’s mercy: 在某人的控制下
We cannot afford a future in which knowledge is at the mercy of popularity and money.
在知识受流行度和金钱支配的未来，我们无法承受之重。
We are otherwise at the mercy of the geopolitical weather.
否则，我们只能听凭地缘政治气候的摆布。