他换工作如此频繁，我已经无法掌握他的动向了。

He changes jobs so often I can’t ___keep ___track any more.

一定要留意时间，以免迟到。

Be sure to ___keep ___track of the time so you won't be late.

试图通过翻译来跟踪这些变化是不合适的任务。

Trying to ___keep ___track of these changes by translating them would be an inappropriate task.