after entering the middle school,i ()have the happy time any more这里为什么用entering,后面应该用什么时态

表示正在进行时。

after+doing. 后面结合语境。
比如 after studying math in extre class, i had improved my math grade that year.
after entering the class, i find teacher standing in front of the rest students.
after going USA, i wish i could try my best in my English learning.

didn't
entering the middle school 是动名词作介词After的宾语