新概念英语第四册第26课 The past life of the earth
①It is animals and plants which lived in or near water whose remains are most likely to be preserved, for one of the necessary conditions of preservation is quick burial, and ②it is only in the seas and rivers, and sometimes lakes, where mud and silt have been continuously deposited, that bodies and the like can be rapidly covered over and preserved.
第6行：After all, all living creatures live by feeding on something else, whether it be plant or animal, dead or alive, and ③it is only by chance that such a fate is avoided.
第9行：When you think of the innumerable birds that one sees flying about, not to mention the equally numerous small animals like field mice and voles which you do not see, ④it is very rarely that one comes across a dead body, except, of course, on the roads.
第15行：⑤It is always due to some very special circumstances that traces of land animals survive, as by falling into inaccessible caves, or into an ice crevasse, like the Siberian mammoths, when the whole animal is sometimes preserved, as in a refrigerator.
笔者在对《新概念英语》的教学中，把对强调句的把握分为 识别 与 理解 两个步骤，以图真正让学生见到强调句时能准确地识别，然后正确地理解之。