一句话,there's so much that has gone on in the last few months这

there's so much that has gone on in the last few months .
可以看出是一个there be句型,所以's是is
时态嘛~“that has gone on in the last few months”是so much 的定语从句,用于修饰so much 的.has gone是现在完成时.不过既然主句是“there is .”,那主句的时态就是一般现在时
再举例：
1.There is a tree that has grown in my garden since I was a child.
2.She is a student who has been in the USA for over 4 years.
这些都是主句是一般现在时,定语从句是现在完成时的句子