15. An awful crash between an express train and a bus _____ , however, occur the other day in Russia.A. does B. did D. has to D. had to
He was ill. _____ is why he didn't attend the meeting.
Will he come back to school tomorrow? I hope _____.
The students encouraged _____ to go on.
-- Who broke the glass? - I suppose _____ must be one of the children.
She cut the cloth with _____ scissors.