focus on 的具体用法是什么？

Question

focus on 后面➕do的什么形式

Answer 1

focus on ，接名词、代词或者doing动名词形式或者名词性从句，意思是集中做什么。
He prefers to focus on the positive.
他更愿意关注积极面。

What I'm going to do in this lecture is focus on something very specific.
我在这次讲座中将集中讲解非常具体的问题。

Answer 2

focus on后面应该要加动名词也就是doing的形式。专注于（名词）。

Answer 3

介词后的动词要用ing形式。

Focus on writing the sentences.

Focus on the main ideas.