广东省惠州市惠东中学高三英语一轮复习单元自测 book3 unit4(无答案)

Unit 4 How life began on the earthFor several billion years after the “Big Bang”, ____1____ earth was still just a cloud of dust. ____2____ it was to become was uncertain until between 4.5 and 3.8 billion years ago when the dust settled into a solid globe. The earth became so violent ____3____ it was not clear whether the shape would last or not. It exploded ____4____ (loud) with fire and rock. They were in time to produce carbon, nitrogen , water vapour and other ____5____ (gas) , which were to make the earth’s atmosphere. What is even more important ____6____ (be) that as the earth cooled down, water began to appear on ____7____ (it) surface.Water had also appeared on other planets like Mars but, unlike the earth, it had disappeared ____8____ (late). It was not immediately obvious that water was to be fundamental to the ____9____ (develop) of life. What many scientists believe is that the continued presence of water allowed the earth to dissolve harmful gases and acids into the oceans and seas. This produced a chain reaction, ____10____ made it possible for life to develop.语法填空：Many millions of years later, the first ____1____(extreme) small plants began to appear on the surface of the water. ____2____ multiplied and filled the oceans and seas with oxygen, ____3____ encouraged the later development of early shellfish and all sorts of fish. Next, green ____4____ (plant) began to grow on land. They were followed in time by land animals. Some were insects. Others, ____5____ (call) amphibians, were able to live on land as well as in the water. Later when the plants grew into forests, reptiles appeared ____6____ the first time. They produced young ____7____ (general) by laying eggs. After that, some huge animals, called dinosaurs, developed. They ____8____ (lay) eggs too and existed on the earth for more than 140 million years. However, 65 million years ago the age of the dinosaurs ended. Why they suddenly disappeared still remains ____9____ mystery. This disappearance made possible rise of mammals on the earth. These animals were different from all life forms in the past, because they gave birth ____10____ young baby animals and produced milk to feed them.A visit to the moonm语法填空：Before we leave, Li Yanping explained ____1____ me that the force of the gravity would change three times ____2____ our journey and that the first change would be the most powerful. Then we were off. ____3____the rocket rose into the air, we were pushed back into our seats because we were trying to escape the pull of the ____4____ (earth) gravity. It was so hard ____5____ we could not say anything to each other. ____6____ (gradual) the weight lessened and I was able to talk to him. “ Why is the spaceship not falling back to the earth? On the earth if I fall from a tree I will fall to ground.” I asked. “ We are too far from the earth now ____7___ feel its pull, “ he explained, “ so we feel as if there is no gravity at all. When we get ____8____ (close) to the moon, we shall feel its gravity ____9____ (pull) us, but it will not be as strong a pull ____10____ the earth’s. “ I cheered ____11____ immediately and floated weightlessly around in our spaceship cabin ____12____ (watch) the earth become smaller and the moon larger.When we got there, I wanted to explore immediately. “ Come on,” I said. “ If you are right, my mass will be ____1____(little) than on the earth because the moon is smaller and I will be able to move more freely. I might even grow taller if I stay here long enough. I shall certainly weigh less!” I laughed and climbed down the steps from the spaceship. But when I tried to step forward, I found I was carried twice as far ____2____ on the earth and fell over. “ Oh dear,” I cried, “____3____ (walk) does need a bit of practice now that gravity has changed.” After ____4____ while I got the hang of it and we began to enjoy ____5____ (our).Leaving the moon’s gravity ____6____(be) not as painful as leaving the earth’s. But returning to the earth was very ____7____ (frighten). We watched, amazed as fire broke ____8____ on the outside of the spaceship as the earth’s gravity increased. Again we were pushed back hard into our seats as we came back to land. “ That was very ____9____ (exhaust) but very exciting too,” I said. “Now I know much more about gravity! Do you think we could visit some stars next time?” “Of course,” he smiled, “____10____ star would you like to go to?”。