30．　　　　 the meeting himself gave them a great deal of encouragement．

　A．The president will attend　　 　　　 B. The president to attend

　C．The president attended 　　　　 　　D. The president’s attending

29. As a beginner in English, we should acquire as much knowledge as possible, ________ our communication skills.

A. which are based　 B. upon which are based 　C. which are based upon　 D. to which are based

28．I can think of many cases ___ students obviously knew a lot of English words and expressions but couldn’t write a good essay.

A. why　　 B. which　　　　　　 C. as　　　 D. where