what months are in this season?

应该用：
What months are there in this season?
回答：
There are June,July and August in summer.
不用定冠词the
因为是泛指所有的summer
题目的问法,在语法上没有错,可以这么说.但是回答时要说：
June,July and August are in summer
the summer 和 summer 是有不同的：
in summer指的是一般的夏天.
比如：Most people like to swim in summer,but some are fond of swimming in winter.大多数人喜欢夏天游泳,有些人喜欢冬天游.
in the summer指某个特定的夏天.比如：
I will go to Tibet in the summer.
为了强调也会说“in this summer”,不过人们更习惯省掉in.

Which months are in this season?
Junne, July and August are in summer.

speak like this:
which months are there in each season?
in spring, there are ...
in summer, there are..
...
..

都可以，用There are June,July and August in the summer更好一些