通信双方必须共同遵守的(),如通信过程的同步方式、数据格式、编码等,称为计算机网络协议(Protocol)。
A.规则
B.方法
C.约定
D.A和C
参考答案:D
铝土矿的主要成分是Al2O3,请按要求进行计算:
(1)Al2O3中铝元素与氧元素的原子个数比为______.
(2)Al2O3中铝元素与氧元素的质量比为______.
(3)求Al2O3中铝元素的质量分数______(计算结果保留至0.1%)
根据汉语提示完成句子。
1. Jim is good at swimming. He could swim _______ (在五岁时).
2. How could you _______ (对……说谎) me?
3. —Do you like _______ (照相)?
—Yes, 1 do.
4. —_______ (多宽) is your desk?
—It's 50 centimeters wide.
5. Some young people MP3 _______ (用……做) listen to music.