【错误表达】

He is unable to improve the suggestion.

他提不出更好的意见。

【讲解辨析】

Improve用作及物动词，是改进改善的意思。当表述把......改善得更好或做出比......更好时，improve是不及物动词，应该与介词on或upon连用。

【正确表达】

He is unable to improve on the suggestion.

He is unable to improve upon the suggestion.

【举一反三】

She has improved her suggestion.

她已经修改了她的建议。

The teacher wanted me to improve on that piece of work.

导师要求把那件作品改得更好。