Question

he has just finished什么his homework do的什么形式

Answer 1

应该用do的动名词形式doing。即He has just finished doing his homework.

固定搭配:finish sth./doing (sth.)

Answer 2

填doing
固定用法 finish doing sth

He has finished doing his homework.
他已经完成作业了。

Answer 3

答：应该说：

He has just finished doing his homework.

动词finish后面习惯接上doing sth. 

类似的动词还有allow 允许;consider考虑;enjoy 喜爱;avoid避免;give up 放弃;imagine 想像;keep 保持;mind 介意;miss 没赶上;permit 允许;practise 练习;prevent 阻止;risk 冒险;stop 停止;suggest 建议;understand 理解等。

例如：

I am considering making a new plan.  我正在考虑制定新计划。

She enjoys helping her parents with the housework.  她喜欢帮她母亲做家务。