掌握 grasp; know well; [例句]学生们掌握了小数、
百分数和分数。The students had a grasp of decimals, percentages and fractions.
master 意思： 掌握 [例句] to master new skills/techniques 掌握新的技能 / 技术
精通 master 动词; Proficient（形容词）
词组 be proficient in [at]; Proficient in English 精通英语
[例句]她非常精通音乐。She was very proficient in music.
词组 have a good command of; 词组 be good at;