未知题型 A．They'd have to get permission.B．Jack wouldn't like it.C．He thinks it might work.D．The other assistants should be consulted.

未知题型 听力原文： Clay is found almost everywhere in the world. (32) It is formed by the action of wind and water on rocks over thousands of years. The rocks change in both chemical and physical ways. Chemically, elements are added and taken away. Physically, the rocks break down into smaller and smaller pieces. After a long time, some of the rock changes to clay. (33) Clay is important because it is used around the world to make containers of all kinds. Potters add water to soften the clay. This makes it easier to form. into shapes by hand or by machine. Then it is fired in an extremely hot stove. The result is a container with a hard surface that will last for many years. You can usually find good clay (34) in low areas of islands or land, especially if volcanoes helped form. the land. (34) Clay often exists in fields covered with some water. The clay will be found about one meter below the ground. (34) River banks often also have clay about one meter or less under the surface. You can recognize clay (35) because it is very shiny when it is wet. You can also perform. a test. Take some of the material and add enough water to it to make it seem like you are making bread. Then press it in your hand until it is about the size of an egg. It is probably clay if it holds together instead of falling apart when you stop pressing.(33)A．The natural force makes it come into being.B．It originates from some chemical elements in the nature.C．It comes from the rocks with the action of wind and water.D．A series of biological changes happen in the process.

未知题型 Another thing an astronaut has to learn about is eating in space. Food is weightless, just as men are. Food for space has to be packed in special ways. Some of it goes into tubes that a man can squeeze into his mouth. Bite-sized cookies are packed in plastic. There is a good reason for covering each bite. The plastic keeps pieces of food from travelling in the spaceship. On the earth very small pieces of food would simply fall to the floor. But gravity doesn' t pull them to the floor when they are out of the plastic in a spaceship. (78) They move here and there and can get into a man' s eyes or into the spaceship' s instruments. If any of the instruments is blocked, the astronauts may have trouble getting safely home. As astronauts travel on longer space trips, he must take time to sleep. An astronaut can fit himself to his seat with a kind of seat belt. Or, if he wants to, he can sleep in a sleeping bag which is fixed in place under his seat. But be careful he must put his hands under the belt when he goes to sleep. This is because he is really afraid that he might touch one of controls that isn' t supposed to be touched until later.Why would astronauts cover each bite of food in space?A．Because small pieces of food would fall down to the floor.B．Because weightless pieces of food might make trouble when they travel around.C．Because they haven' t enough food for longer trips.D．Because astronauts don' t want to waste food.