他很自私。

He's selfish. *selfish 带有轻视的语气，表示“自私的”、“利己的”、“不考虑别人的”。

I don't like John. (我不喜欢约翰。)

Why? (为什么?)

Because he's selfish. (他太自私了。)

He's self-centered. (他总是以自己为中心。)

He's self-serving. (他是个只顾自己的人。)

He only cares about himself. (他只想他自己的事。)

He doesn't care about anyone but himself. (他从来不想别人。)

他总把问题想得过于严重。

He takes things too seriously.

他头脑简单。

He's simpleminded. *simpleminded“单纯的”、“头脑简单的”，也有“无知的”、“愚蠢的”语感。