find sb do/doing sth 變成被動的時候也不用加to
加to的是感官或使役動詞
把這句話補充完整就是
anyone who was/is found trying to take petrol on board trains would be stopped.
結(jié)構(gòu)是這樣的
主句為 anyone would be stopped
然后anyone后面跟了一個過去分詞做后置定語,補充完整就是定語從句.從句中是被動語態(tài),find sb doing sth--find anyone trying to take petrol那你變成被動的時候不是 anyone who is found trying.
至于你說的為什么不用being found to try to take因為你是發(fā)現(xiàn)的時候正在攜帶汽油, 所以要用find sb doing sth 而不是 who was/is being found正在被發(fā)現(xiàn) 陳述一個事實,不用正在進行時
明白不?