单项选择题 （）from endless homework on weekends, the students now find their own activities, such as taking a ride together to watch the sunrise.

单项选择题 Thank you for sending us（）fresh vegetables of many kinds. You have done us（）great service.

多项选择题 努力营造宽松、民主、和谐的教学气氛是教师必须注意的教学原则，为此，教师应该______。