not until.heard from
until 用于強(qiáng)調(diào)時間的強(qiáng)調(diào)句型：
It is (was) not until … that " 直到 … 才 " ,此時不可以用 till 代替.
It was not until yesterday that I got your letter/heard from you.
直到昨天,我才收到你的來信.
強(qiáng)調(diào)句型
It is (was) +被強(qiáng)調(diào)部分+ that (who) + 句子其他部分.(當(dāng)強(qiáng)調(diào)的部分是人,且為句子的主語時,才用 "who",其余用that.)
強(qiáng)調(diào)句去掉It is (was)...that 之后還是一個完整的句子.
此結(jié)構(gòu)強(qiáng)調(diào)的成分僅限于主語,賓語和狀語.
I原句：My father did the experiment in the lab yesterday evening.
強(qiáng)調(diào)主語：It was my father who did the experiment in the lab yesterday evening.
強(qiáng)調(diào)賓語：It was the experiment that my father did in the lab yesterday evening.
強(qiáng)調(diào)時間：It was yesterday evening that my father did the experiment in the lab.(注意不用when)
強(qiáng)調(diào)地點：It was in the lab that my father did the experiment yesterday evening.