It is only gradually, with the passing of years, _____ to a clear understanding of their position.

It was on October 1st _____ new China was founded.

It was in New Zealand _______Elizabeth first met Mr Smith .

I don’t remember how many years ago____ State Street began its business in China.

---Do you know _______________________ won high click rate in micro-blogs?
---It was the teachers’ wonderful chorus in the New Year’s gala.

It was with great joy _______ he worked out the problem that he had long been puzzled about.

It was at this shop _______ I bought my skirt. How about coming to my home to have a look tonight?

It was not until midnight________they reached the camp site.
A,that    B,when     C,while    D,as

-------What is it       made Carl determined to give up smoking?
--------Watching how his father died in pain from lung cancer.

It was in the lab ______ was taken charge of by Professor Harris _______ they did the experiment.