[填空题]Scientists have discovered evidence of the world’s earliest animals, (36) back 635 million years, before the end of the last ice age. Scientists have found evidence of the world’s earliest multicellular animal life, sponges 408 million years older than the oldest known dinosaur remains, 100 million years older than when scientists thought the first animal life (37)
Earth scientist Gordon Love of the University of California, Riverside (38) the team that made the discovery. He says the 635-million-year-old fossils were found in sedimentary rocks in a (39) in southern Oman and are in the form of steroids, essential biochemicals in the cell membranes of sponges.
"Some of the natural products produced by sponges produce very (40) structures," said Love. "Even when they get (41) for hundreds of millions of years in sediments. Basically when the structures of the molecules get tweaked a little bit, we can still

[填空题]Scientists have discovered evidence of the world’s earliest animals, (36) back 635 million years, before the end of the last ice age. Scientists have found evidence of the world’s earliest multicellular animal life, sponges 408 million years older than the oldest known dinosaur remains, 100 million years older than when scientists thought the first animal life (37)
Earth scientist Gordon Love of the University of California, Riverside (38) the team that made the discovery. He says the 635-million-year-old fossils were found in sedimentary rocks in a (39) in southern Oman and are in the form of steroids, essential biochemicals in the cell membranes of sponges.
"Some of the natural products produced by sponges produce very (40) structures," said Love. "Even when they get (41) for hundreds of millions of years in sediments. Basically when the structures of the molecules get tweaked a little bit, we can still

[填空题]Scientists have discovered that plants themselves produce many poisonous chemicals for{{U}} (36) {{/U}}against insects. But insects have developed ways of{{U}} (37) {{/U}}with them and, in fact, have been eating plants for about 250 million years. Now insects are using these same{{U}} (38) {{/U}}to deal with man-made poi sons--insecticides. This is why{{U}} (39) {{/U}}of insects to insecticides has developed so{{U}} (40) {{/U}} What should be done Scientists studying the problem suggest that farmers use less insecticides. At the moment, farmers{{U}} (41) {{/U}}spray crops as a{{U}} (42) {{/U}}against problems that are caused by large number of pests. They should, instead, spray only where pests have actually been seen. Secondly, farmers could use a{{U}} (43) {{/U}}of two or three insecticides at once.{{U}} (44) {{/U}} The most surprising suggestion, perhaps, is that at certain times of the year,{{U}} (45) {{/U}}. The new insects will mate with those which