I used to play tennis.I stopped playing a few years ago. 請問為什麼stopped後面的 play要加ing呢?

stop這個動詞在接「不定詞」或「動名詞」時，會有不同的意思：
He stopped smoking.=他戒煙了。（停止吸煙）
He stopped to smoke. = He stopped in order to smoke. =他停下來吸煙（為吸煙而停下來）。

I used to play tennis. I stopped playing a few years ago.
我以前有打網球的習慣。但幾年前，我停掉了這個習慣。（用動名詞playing)

這兩句中文
我以前有在打網球
幾年前我停止不打網球了

stopped後面的 play要加ing
就是說stop停止 play(網球)這個動作了

participle is technical, one of the forms of a verb(play) that are used to make tenses. In English, present participles end in --ing and past participles usually end in --ed or --en (played.)
I stopped (verb)
playing---present participle;
Hence avoid two verbs in a sentence= verb+ a verbal.
Hence:-Participial in a perfect tense:-eg:Not absolute tense:-eg:-10 marks:--
Having stopped playing tennis, I got the cup JP006.usa.