问题
单项选择题
磨硬的工件时，应选择较（）的砂轮
A.硬
B.软
C.中
答案
参考答案：C
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磨硬的工件时，应选择较（）的砂轮
A.硬
B.软
C.中
参考答案：C
| 完形填空 | ||||
| Vitamins(维生素) are a discovery of the 20th century. A hundred years 1 , no one knew anything 2 them. The vitamins are 3 by letters of alphabet. Vitamin A 4 by the eyes. There is vitamin A in milk, butter and green vegetables It 5 by the body. Vitanun B must be supplied (提供) 6 by some of our food. The skins 7 grains of all sorts have vitamin B in them. Vitamin C is very important 8_ the body. Without it 9 teeth will become loose and their arms and legs become weak. Oranges and tomatoes 10 vitamin C in them. There are other vitamins. But these A, B,C are the most important. | ||||
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