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
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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
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| 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. |