问题
选择题
硼有两种天然同位素510B、511B,硼元素的相对原子质量10.80,则对硼元素中510B原子百分含量的判断正确的是
A.20% B.略大于20% C.略小于20% D.80%
答案
答案:A
十字交叉法很容易知道答案为A
硼有两种天然同位素510B、511B,硼元素的相对原子质量10.80,则对硼元素中510B原子百分含量的判断正确的是
A.20% B.略大于20% C.略小于20% D.80%
答案:A
十字交叉法很容易知道答案为A
任务型阅读. | ||||||||||||||||||
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根据上面的表格用一个或两个词完成下面句子. | ||||||||||||||||||
1. If you go to , maybe some people can understand you. 2. Egyptians speak . 3. If you go to , you must learn Russian well. 4. The capital of Singapore is . 5. From the form ( 表格), we can see that is the most important language. |