It’stime（）class.Youmust（）theclassroom. A: to；togo B: for；goto C: to；togoing D: for；togo

Theclassroom needs ,for it’s too dirty. A: A. clean B: B. to clean C: C. being cleaning D: D. to be cleaned

In the past 20 years, teachers have devoted to the reform of theclassroom teaching and learning by introducing different teaching philosophies and learning styles. A: ooming B: temporary C: solitary D: tedious