31.In spite of the extraordinary progress made in science and technology，problems remain in terms of guaranteeing that achievements benefit the greatest number of people.

32.A famous thinker once wrote that “the greatest threat to mankind is mankind itself!” If this is indeed the case，then the current situation should make us ponder our future existence.

33.U.S.President Harry Truman once remarked: “The buck stops here!” His view has been confirmed by numerous world leaders who have assumed full responsibility for their actions.

34.“I feel like I m wasting my time!” That s how one language teacher described her experience at teaching English. Many other teachers have expressed the same sentiment.

35.“A penny saved is a penny earned!” Many people share the same attitude concerning thriftiness.

36.“A1，000li journey begins with the first step.” We often hear the saying，but do we really understand what it means?

37.Large families were once seen as a lessing. Today，however，things are changing and an increasing number of Chinese parents realize that fewer is better.

38.People used to place total reliance on the government. The so-called “iron rice bowl” prevailed in the past，but things are quite different today.

39.Severay years ago，Chinese streets were filled with people wearing identical drab clothing. Today，however，things are quite different and the streets are awash with people wearing fashionable bright colored outfits. Why has the change taken place?

40.Years of observing human behavior has enabled me to conclude that the major difference between mediocrity and success lies solely with the individual concerned. Successful individuals consistently seek advancement，while their less industrious contemporaries are merely content with the status quo.