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.