问题
判断题
系统气密可以用实气进行，但必须氮气置换干燥合格。
答案
参考答案：对
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系统气密可以用实气进行，但必须氮气置换干燥合格。
参考答案：对
| 完型填空. | ||||
| Where's salt from? In the northwest of our country there are __1__ salt lakes. Some __2__ them are very big. The salt in a big lake can meet the needs of our people for __3__ to come. But __4__ of the salt in our country is from the sea. Great holes are dug and __5__ the sea water. When the sun dries up the water, salt can be got __6__ the ground. The salt is white and clean __7__ beautiful. We can't live __8__ salt. we need it in our food. __9__ need it, too, salt is very important __10__ us. | ||||
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