相声是一种以对话为形式的中国传统喜剧表演。它是中国最流行的表演艺术，主要用北京方言进行表演。相声是语言的艺术，也是幽默的艺术。它在内容上是喜剧艺术，在形式上则是对话的艺术。但这两大特点并不是彼此孤立的，而是相互依存的。相声的四大基本功为说、学、逗、唱，其目的是通过诙谐幽默的话语达到娱乐观众的效果。

A. Older people feel thankful for working in a stable environment．
B. Young people feel unpleasant about being paid less than their peers．
C. The success of peers exerts a negative impact on people over 45．
D. Young workers under 45 appreciate a much smaller ttmnel effect．

A. The economic development of Eastern Europe is rather static．
B. People feel satisfied with Denmark"s economic development．
C. The income of others has a positive effect in Germany"s individual corporations．
D. The income of others affects employees" contentment in Denmark"s private firms．

A. a lot of digital equipment
B. the students" continuous progress
C. a great amount of digital information a digital textbook can track
D. parents" and teachers" constant watch over students" development

A. 核糖体
B. 核蛋白
C. 核苷酸
D. 核苷
E. 氨基酸