The medicine always made him feel dopey and unable to concentrate.

那药总让他感到昏昏欲睡且无法集中注意力。

《柯林斯英汉双解大词典》

Are you tired or unable to concentrate during the day?

你是否在白天时感到疲惫或是无法集中注意力？

youdao

Jerusha was unable to concentrate on what Mrs. Lippett said after this. In her heart she was both touched and extremely happy.

接下来李派特太太又说了些什么，洁茹实在无法再专心听下去了。

youdao

The victim said the abuse had left him regularly depressed and unable to concentrate.

BBC: Ex-Isle of Wight choirboy compensated for priest abuse

His 15-year-old brother is taking high school exams this month, but says he is unable to concentrate.

WSJ: Victim's Family in India Still Reels

He became forgetful about discussions and appointments, and he was unable to concentrate or focus, the suit said.

CNN: January 24, 2013 -- Updated 1044 GMT (1844 HKT)