That would be someone who is scatterbrained.

那将是一个心不在焉的人。

If you say to someone you are scatterbrained, it is not nice.

如果你对某人说你心不在焉， 那可不好。

He was tired of the scholastic scholasticism and scatterbrained in class.

他厌倦了学校的烦琐哲学，上课时注意力不集中。

They seem not to fly of their own volition, but, scatterbrained, to be tossed from tree to tree like wind-blown leaves.

它们似乎不是自愿飞翔，而是漫不经心地像被风吹落的树叶一样从一棵树扔到另一棵树。

But Scarlett intended to marry — and marry Ashley — and she was willing to appear demure, pliable and scatterbrained, if those were the qualities that attracted men.

要同艾希礼结婚----并且乐意装出一副貌似庄重、温顺而没有主见的模样，如果这些品性真正能够吸引男人的话。