---______ the farmers discovered the entrance to the secret cave in the valley?
--- Totally by chance.

Was it in Disneyland, ________ many cartoon characters can be seen, ________ the film was set?

It is his dishonesty _________ leads to his failure in his struggling for the job.

----- It was at that moment_________ her appointment with the doctor.

Is it on September 1^st _____ students come back to school every year ?

It was ten years ago__________he was put into prison because he fought against the government.

. It was in this house ________ he heard some strange sounds.

Mike didn’t understand _______ made his wife so upset this morning.

— Why didn’t they complete the task in time?
— Because it was not until late afternoon _____ they began to solve the major problem．

It was because of the bad weather ______ the sports meet was put off.