21.用怪罪别人的办法来解决问题通常被称为寻找替罪羊。22. The chief foods eaten in any country depend largely on what grows best in its climate and soil.22.一个国家的主要食物是什么，大体取决于什么作物在其天气和土壤条件下生长得最好。23. Over a very large number of trials, the probability of an event’s occurring is equal to the probability that it will not occur.23.在大量的实验中，某一事件发生的几率等于它不发生的几率。24. Most substance contract when they freeze so that the density of a substance’s solid is higher than the density of its liquid.24.大多数物质遇冷收缩，所以他们的密度在固态时高于液态。25. The mechanism by which brain cells store memories is not clearly understood.25.大脑细胞储存记忆的机理并不为人明白。26. By the middle of the twentieth century, painters and sculptors in the United States had begun to exert a great worldwide influence over art. 26.到了二十一世纪中叶，美国画家和雕塑家开始在世界范围内对艺术产生重大影响。27. In the eastern part of New Jersey lies the city of Elizabeth, a major shipping and manufacturing center.27.伊丽莎白市，一个重要的航运和制造业中心，坐落于新泽西州的东部。28. Elizabeth Blackwell, the first woman medical doctor in the United States, founded the New York Infirmary, an institution that has always had a completely female medical staff.28. Elizabeth Blackwell，美国第一个女医生，创建了员工一直为女性纽约诊所。29. Alexander Graham Bell once told his family that he would rather be remembered as a teacher of the deaf than as the inventor of the telephone.