He could have finished it on schedule, but __________ he fell behind.
—We didn’t find the Blacks ________ the lecture.—No one had told them about ________ a lecture the following day.
His first book ________ next month is based on a true story.
In order to improve English,________.
The global warming is more and more serious,for which human beings ________.
Taking this medicine,if________,will of course do good to his health.