身不由己的英文：
[Literal Meaning]
body/not/follow/oneself
One can not control his body.

[解释]
由：听从。身体不能由自己作主。指行为不能由自己支配。

[Explanation]
be forced to do something

[例子]
父母对他的要求很严，他也是身不由己，晚上不能和你们一起出去玩。

[Example]
He is at the mercy of his parents and cannot go out with you tonight.

[英文等价词]
at the mercy of

After the usher had been given twenty strokes she had to return to kowtow to Xifeng.
"那人身不由己,已拖出去挨了二十大板,还要进来叩谢."

He must needs swim that is held up by the chin
身不由己,只得从命

We were seized by a sudden impulse to run.
我们身不由己突然想跑。

I was sliding(about)helplessly (on the ice).
我(在冰上)身不由己地滑起来了.

He drifts around on the outskirts of her group for a month
他身不由己地围着她那一伙同道团团转，一转就是一个月。

Still I involuntarily obeyed him, as if I was not quite sure
我还是身不由己地服从了他，好象是我也没有弄明白似的。