飞机在5000英尺高空飞行。

The plane is ___flying at 5000 feet.

这只可怜的鸟不能飞，因为它的翅膀断了。

The poor bird couldn't ___fly because it had a broken wing.

一看到我们，鸟就飞走了。

As soon as it saw us, the bird ___flew away.