I build my dreams — and to do that, you have to be able to think clearly.

我构建了我的梦想——为了实现它，你就必须能够清晰地思考。

It means the person is rational, is able to think clearly.

这意味着这个人是理性的，能够清晰地思考。

I'll be able to think more clearly and figure this out.

我的思路才能更清晰 来查清这件事。

You may have a difficult time focusing. You may not be able to think clearly about a problem. Dehydration can also cause headaches.

你可能很难集中注意力；你可能无法清楚地思考问题；脱水还会引起头痛。

There are folks who are deeply concerned that students will not be able to think clearly if you don't ever learn to write well.

有些人非常担心，如果没有学好写作，学生就无法清晰地思考。

Hamed is saying that the medication is impairing Sue's better judgment; she's not able to think clearly because of the drugs she's been taking.

Hamed 说药物正在损害 Sue 更好的判断力；由于一直在服用药物， 她无法清晰地思考。