D Antarctica is the southernmost place on Earth, and it is larger than the United Sates and 95% of it is covered with ice. The ice is 5 kilometers thick at places and it never melts. At least that is what we thought, but let us keep it that way for now. The ice seems to be alive as it works its way towards the seA． It forms an ice shelf over the water. The edge breaks away from the shelf and falls into the seA． From here it drifts. Now big pieces of ice become icebergs that can be 160 km long. They now drift north until they finally melt and become part of the ocean. This process is part of a bigger process which in turn forms a cooling system for Earth. This is so important that no country is allowed to control this areA． The treaty (agreement) signed by 12 countries at first and later joined by more, was to prevent any country harming the planet with irresponsible behavior. The treaty basically states that: Antarctica can be used for peaceful purposes only. No country may build a military base there. No country may do a nuclear test there. No country may dump nuclear waste there. Scientists working there will share their information. Some other rules are there to protect the penguins and seals. No dogs may run loose. No planes may land near large groups of animals. No guns, explosives, or tractors may be used near the animals. Most important is that every member can inspect any of the other bases if he suspects that the treaty rules are being broken. While the treaty is not foolproof（万无一失的）, it does play a very important part in the protection of AntarcticA． The more people realize the effects that pollution has on this continent, the bigger the pressure will be on Governments to change the way they look at pollution. 69．Why was it important to sign a treaty for Antarctica? A．Because the ice on Antarctica will finally melt into the ocean. B．Because Antarctica is covered with 5 kilometers thick ice. C．Because Antarctica balances the temperature of Earth. D．Because there are many big icebergs in AntarcticA． 70．What is the process of the movement of ice in Antarctica? A．Ice shelf---sea water---iceberg---ice. B．Sea water---ice---iceberg---ice shelf. C．Iceberg---ice shelf---ice---sea water. D．Ice---ice shelf---iceberg---sea water. 71．What is included in the Antarctica treaty? A．There is no secret research information in AntarcticA． B．Dogs are not allowed to be raised in AntarcticA． C．Waste can’t be thrown away in AntarcticA． D．People can’t bring their guns to AntarcticA．