问题
单项选择题
烘炉过程中，500℃恒温的目的是（）。
A、脱除耐火材料的表面水份
B、脱除耐火材料中的结晶水
C、烧结耐火胶泥
D、暖炉
答案
参考答案：C
搜题请搜索小程序“爱下问搜题”
烘炉过程中，500℃恒温的目的是（）。
A、脱除耐火材料的表面水份
B、脱除耐火材料中的结晶水
C、烧结耐火胶泥
D、暖炉
参考答案：C
| 用所给词的适当形式填空，其中有两项多余。 | |
| |
| There are a lot of trees around us. The trees can help to make the air 1 and cleaner. They can also help to 2 the weather. They provide(提供) humans with food, 3 , medicine and other things. Because of the trees, many animals can live 4 the earth. But people often cut trees down in large numbers. The forests are becoming much 5 than before, so we should protect them well. |