你的句子是正確的
只要主要子句的動(dòng)詞不是過(guò)去式,也不是過(guò)去完成式,那麼附屬子句的動(dòng)詞可以是任何可以正確表達(dá)意思的時(shí)態(tài).然而,如果主要子句的動(dòng)詞是過(guò)去式或過(guò)去完成式,那麼附屬子句的動(dòng)詞就必須是過(guò)去式或過(guò)去完成式.這個(gè)規(guī)則的例外是,附屬子句是在表達(dá)眾所周知的普遍事實(shí)和真理：
In the 1950s,English teachers still believed that a background in Latin is essential for an understanding of English.
Columbus somehow knew that the world is round.
Slaveowners widely understood that literacy among oppressed people is a dangerous thing.http://www.cybertranslator.idv.tw/grammar/sequence.htm看下這個(gè)網(wǎng)站