Please excuse me _______ your letter by mistake.
______ is no possibility _____ the shy girl can win the first prize in the English speech contest.
Generally speaking, nobody will work with _____ has a bad virtue.
— Have you found your English book? — I am not sure ____ I could have left it.
The art center is ______ used to be Factory 789 and _______ millions of tractors were made.
____ students should be given more free time is suggested by many experts and welcomed by kids in school.