It was here that he differed from an Englishman.
It was only then that I began to learn the unpalatable truth about John.
It was yesterday that my secretary sent the bill to Mr Harding.
所谓副词性短语，就是指起副词作用可用状语的短语，如last week， some time ago， three days later等。如：
It was about 600 years ago that the first clock with a face and an hour hand was made.
It was only last February that he announced he would run for president.
It was last night that John wore his best suit to the dance.
It was through hard work that he succeeded.
It was only after his death that she learned of his affair with Betty.
It was along the Mississippi River that Mark Twain spent much of his childhood.
It was for this reason that her uncle moved out of New York and settled down in a small village.
It is only on the world market that we can prove the competitiveness and quality of our goods.
It was thanks to your stupidity that we lost the game.
It was after he got what he had desired that he realized it was not so important.
It was because I wanted to buy a dictionary that I went to town yesterday.
It was only when I read her letter that I realised what was happening.
not...until...句式中的until可能是介词(用于引出介词短语作状语)也可能是连词(用于引出从句作状语)。这类句式的基本结构是It is (was) not until...that...(注意that后面的句子要用肯定式)。如：
It was not until the meal was over that he turned up.
It was not until I met you that I knew real happiness.
It was not until 1911 that the first of the vitamins was identified.
It was not until I saw him laughing that I realized what a fool I had been.