His eyes were so tired that he had difficulty focusing them.

他的眼睛累了，调节焦距困难。

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A child will have difficulty focusing his or her attention, if the proprioceptive system is not fully formed or integrated yet.

如果本体感受系统没有完全形成或者仍未一体化，则孩子难以专注。

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They started out in school with higher levels of aggressive and disruptive behavior and more difficulty focusing and cooperating.

他们在学校中表现出强烈的好斗，很难集中注意力与同学合作。

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The new AF Focus Illuminator is a supplemental light included for those times when auto focus has difficulty focusing in dark places, or in scenes with particularly low contrast.

ENGADGET: Olympus Stylus TG-625 Tough adds AF light for tricky shots in rough situations

It is typical during initial post-trauma weeks to have difficulty sleeping, eating or focusing on other things.

WSJ: First Responders Seek Out Counseling as Attitudes Shift

Company schemes can keep costs down by focusing on the default fund, the option that employees end up with (since they have difficulty making their own choice).

ECONOMIST: Workers are sleepwalking towards an impoverished old age