1.official adj.官方的；正式的；公务的
Both English and French are official languages(官方语言) in Canada.
2.base vt.以……为根据 n．基部；基地；基础
①Based(base) on his own experience when he was studying in Harvard University, his story is very moving.
②Having a good command of Chinese is a basic(base) need to live in China.
3.latter adj.较后的；后半的；(两者中)后者的
①I have two good friends, Mary and Lily, the former is good at dancing, the latter(后者) can speak Danish fluently.
②A few years later(late), I came across on the way to my home.
4.command n．& vt.命令；指令；掌握
①I got along well with the girl who has a good command of(精通) the German language.
②I’m at your command—what would you like me to do？
③He commanded that everyone should make(make) good use of this chance.
＝He commanded everyone to make(make) good use of this chance.
