exist|exists|existed|existing

贫困在这个国家仍然存在。

Poverty still ___exists in this country.

鬼魂根本不存在。

Ghosts don't ___exist anyway.

公交车将不再存在，每个人都会有自己的车和自己的电脑。

Buses will not ___exist any more and everyone will have his own car and his own computer too.

没有干净的空气，人类无法长期生存。

You cannot ___exist without clean air for an extended period.

在如此贫困的条件下，没有外部援助几乎无法生存。

It's nearly impossible to ___exist in such poverty without external aid.

一些微生物可以在深海热液喷口等极端环境中生存。

Some microorganisms can ___exist in extreme environments like deep-sea vents.

这个新软件将使所有现有的流程快得多。

This new software will make all ___existing processes much faster.

现有的图书馆非常小，需要扩建。

The ___existing library is quite small and needs expansion.

那座现存的图书馆建筑已有一百多年的历史。

The ___existing library building is over a hundred years old.

新软件极大地改进了现有的系统。

The new software greatly improved the ___existing system.

在做出改变之前，我们需要审查现有的政策。

We need to review the ___existing policies before making changes.

现存的教育体系需要进行重大改革。

The ___existing education system needs significant reform.

恐龙在数百万年前就已经存在。

Dinosaurs ___existed millions of years ago.