他不太善于清楚地表达自己的思想。

He's not very good at getting his ideas across.

《牛津词典》

他说得太快了，不能清楚地表达自己的意思。

He spoke so fast that he couldn't express himself clearly.

youdao

这个小男孩可以毫无困难地用英语清楚地表达自己的意思。

The little boy has no difficulty expressing himself clearly in English.

youdao

Now if that's what they mean,then--a small observation-- they didn't express themselves very clearly.

如果这就是他们的意思，小小观察一下-,他们并没有把自己表达地很清楚。

耶鲁公开课 - 死亡课程节选