Please excuse me _______ your letter by mistake.
Many experts stick to the view _____ teacher development is _____ the key to quality education lies.
I have to go to school by bus because my bicycle _____.
The course books are _____ by four tapes, which are beneficial to beginners.
— I’m afraid what I did cannot satisfy your requirements.— _____. At least you tried.
While _____ music is just so-so, _____ story in this TV play is quite moving.