5.A good teacher is ________who is always doing things for the good of the students.
The reason for their failure, you know, was _______ they didn’t get fully prepared for it.
John promised his parents he _______ not smoke again, and he has not smoked ever since.
My brother left home five years ago. I _______ nothing from him up to now.
The power to our region has been _______ by the heavy snow.
______more effectively with foreign firms, many Chinese firms have turned to new technology.