Although the ecosystem concept was very popular in the 1950s and 1960s, it is no longer the dominant paradigm. ■ Gleason's arguments against climax and biome are largely valid against ecosystems as well. ■ Furthermore, the number of interactions is so great that they are difficult to analyze, even with the help of large computers. Finally, younger ecologists have found ecological problems involving behavior and life-history adaptations more attractive than measuring physical constants. ■ Nevertheless, one still speaks of the ecosystem when referring to a local association of animals and plants, usually without paying much attention to the energy aspects. ■
要插入的句子：They may be more interested in researching, for example, the adaptations that some aquatic animals undergo to survive in dry desert environments.
我们以TPO15 Passage1 Question12为例：
Leatherbacks keep their body heat in three different ways. The first, and simplest, is size. The bigger the animal is, the lower its surface-to-volume ratio; for every ounce of body mass, there is proportionately less surface through which heat can escape. An adult leatherback is twice the size of the biggest cheloniid sea turtles and will therefore take longer to cool off. Maintaining a high body temperature through sheer bulk is called gigantothermy. ■It works for elephants, for whales, and, perhaps, it worked for many of the larger dinosaurs. ■It apparently works, in a smaller way, for some other sea turtles. ■Large loggerhead and green turtles can maintain their body temperature at a degree or two above that of the surrounding water, and gigantothermy is probably the way they do it. ■Muscular activity helps, too, and an actively swimming green turtle may be 7°C (12.6°F) warmer than the waters it swims through.
要插入的句子：However, these animals have additional means of staying warm.
我们以TPO11 Passage3 Question13为例：
Many signals that animals make seem to impose on the signalers costs that are overly damaging. ■A classic example is noisy begging by nestling songbirds when a parent returns to the nest with food. ■These loud cheeps and peeps might give the location of the nest away to a listening hawk or raccoon, resulting in the death of the defenseless nestlings. ■In fact, when tapes of begging tree swallows were played at an artificial swallow nest containing an egg, the egg in that “noisy” nest was taken or destroyed by predators before the egg in a nearby quiet nest in 29 of 37 trials. ■
要插入的句子：The cheeping provides important information to the parent, but it could also attract the attention of others.
这句话的意思是说吱吱的叫声提供重要的信息给父母，但是也会吸引其他动物的注意。插入的句子承前启后也就意味着前句要出现parent，后句要出现其他的动物。回到段落里面我们发现第二个黑框前面出现了a parent，后面出现了a listening hawk or raccoon，那显然放第二个黑框最合适。