A shell [An arrow] whizzed past.

一枚炮弹[一支箭]嗖地飞过。

《新英汉大辞典》

Why can she live without a shell?

为什么没有壳她还能活下去？

youdao

We can only move slowly, so we need a shell to protect us.

我们只能慢慢地移动，所以我们需要一个壳来保护我们。

youdao

A heavy mortar roared, sending a shell high over the harbor at Charleston,South Carolina.

VOA: special.2009.08.13

So if you think of a shell, you can actually just think of an egg shell, that's probably the easiest way to think of it, where the yolk, if you really maybe make it a lot smaller might be the nucleus.

可以把它想成，个蛋壳，这也许是，最简单的思考办法,蛋黄如果，缩小非常多倍的话,就可以想象成核子。

麻省理工公开课 - 化学原理课程节选

We'll start up a shell and we'll try it. All right, we'll just get out of what we were doing here.

我们开一个shell然后试试，先退出现在的这个来。

麻省理工公开课 - 计算机科学及编程导论课程节选

College admissions ( as Ross Douthat suggests) is a shell game concocted to perpetuate elite privilege.

FORBES: I Went To College, Law School, And Grad School - Because I Wasn't Born Elite

It went public that September, with the ticker THIN, by merging with a shell company.

FORBES: Before... and After

The critter looks like a tiny turtle, but with a shell shaped like a hockey puck.

WSJ: A New Wave of Ocean Explorers | Marvels