1. It's believed that mixed-ability teaching can _______________（促使他们知识的积累和经历的丰富）.
　　2. We _______________（使我们的行为符合别人的）based on a constant mental process of appraisal and interpretation.
　　3. The class are very active. They ________________（争先恐后地回答问题）.
　　4. Oxygen is ________________（一种能和许多物质化合的气体）.
　　5. Mr. Smith is ________________（这次事故的目击者之一）.

　　答案与解析：
　　1. enrich their knowledge and experience
　　2. fit our actions to those of other people
　　3. vie with each other in answering questions
　　4. a gas which unites with many substances
　　5. one of those who have witnessed the accident