時態(tài)是由語境決定的.第一句里 TOM 的 find 這個動作在以前發(fā)生,而后面是不定式,不定式屬于非謂語,非謂語是沒有時間概念的,所謂的非謂語時間概念是由句子謂語來決定.第二句 Some people who are .也沒問題呀 ,只是陳述一個現(xiàn)在的事實,用一般現(xiàn)在時態(tài)也沒錯啊如果是 Tom finds it difficult to support his family. 行不行?第二句如果是 Some people who are successful language learners found it difficult to succeed in other fields.呢?都可以的呀，前面不是說了么 時態(tài)是由語境決定的，行為背景不同而已