英文問題 - ing

這句用了”working on his own”，是因為前面用了prefers ｘｘ　to　ｙｙ，即我較喜愛ｘｘ　多過　ｙｙ，而這是一句比較，所以ｘｘ和ｙｙ都必需是名詞；所以句中，用了動名詞(gerund)這種修辭；所謂動名詞，是以原形動詞+ing之形態做為名詞用者，而使該詞具有動詞和名詞的作用
e.g. He is very fond of (reading) novels
(Lying) late in the morning is a great loss in life.(早晨遲起是人生的一大損失）
(Working) so hard will produce good results(如此努力工作必將獲得好成果）

既然那動詞已經成了名詞，所以就可以用作subject，也可以用作object。在你的句子中就是用”working with others”作主詞片語，而”working on his own”作受詞片語。

動名詞甚至可跟my, his, her, their用
e.g.He insisted on my going there.(他堅持要我去那兒）
e.g. I feel very sorry about his being murdered.（對於他被人謀殺，我感到難過）


其實動名詞非常好用，盼望你去看英文文法書關於動名詞的使用 法。

你句句子有問題
可能應該係咁樣

1. He prefers to work with others but not to work on his own.
2. He prefers working with others but not working on his own.

prefer 後面一定要用ing form ( 如果戈個字係動詞的話), eg. prefer doing / eating

if you use prefer to , then no need to use ing form
prefer to -- to 後面用原動詞 eg prefer to use chopsticks , prefer to read newspaper than magazines

至於你的 working on his own
係一個 phrase
work on ones own 如果變左做 working on ones own is present continous
should be used like this
I'm busy working on my own for the whole project right now.

係唔係 'He prefers working with others than to work on his own.'
please check!~