從句遵循的基本原則是時(shí)態(tài)一致原則.所謂時(shí)態(tài)一致,是在把時(shí)態(tài)確定為三種基本時(shí)態(tài)的基礎(chǔ)上的：過(guò)去時(shí),現(xiàn)在時(shí),將來(lái)時(shí).比如主句用的某種過(guò)去時(shí),從句也要用一種過(guò)去時(shí).這是一般情況.
具體到賓語(yǔ)從句中,主句用一般現(xiàn)在時(shí),從句要根據(jù)在從句中的具體時(shí)態(tài)標(biāo)志來(lái)確定時(shí)態(tài).
she tells me that she will come tomorrow.
she tells me that she won the first prize yesterday.
主句用一般過(guò)去時(shí),從句要用與時(shí)態(tài)標(biāo)志相對(duì)應(yīng)的過(guò)去時(shí)態(tài).比如從句中有過(guò)去具體時(shí)間或者沒(méi)有具體時(shí)態(tài)標(biāo)志,從句用一般過(guò)去時(shí).she told me she won the first prize the day before.從句中有將來(lái)時(shí)間的標(biāo)志,用過(guò)去將來(lái)時(shí)（would（will的過(guò)去式）+動(dòng)詞原形）.she told me she would won the first prize next day.從句中有完成時(shí)態(tài)的標(biāo)志,用過(guò)去完成時(shí).she told me she had been in beijing for 3 years.
主句用將來(lái)時(shí)的很少.從句也用一般將來(lái)時(shí).
特別注意,無(wú)論主句是什么時(shí)態(tài),如果從句句子表示的是一個(gè)不變的事實(shí)或者客觀真理,用一般現(xiàn)在時(shí).the teacher told us the earth goes around the sun.（地球繞太陽(yáng)轉(zhuǎn)是客觀真理）