(1) request指“礼貌地请求某人做某事”，是正式用词，ask较通俗。常用的搭配如：request sb. to do sth.; request sth. (from/of sb.)；跟that从句时要用should+动词原形，或省掉should，直接用动词原形。
- Visitors are requested not to touch the exhibits.
来宾请勿触摸展品。 - All I request of you is that you (should) study hard.
我所要求你的是，你要刻苦学习。
(2) ①beg表示“乞求，乞讨”，可作及物动词，也可作不及物动词。
- He was so poor that he had to beg (for) his bread.
他穷到不得不靠乞讨为生。 - Poverty reduced him to making a living by begging from the rich.
贫穷使他靠向富人乞讨为生。
②beg也表示“恳求，请求”，常用的搭配为：beg sth. of sb.； beg (of) sb. to do sth.。
- May I beg a favor of you?
请帮个忙好吗？ - I beg (of) you not to say anything like that to Ann.
我请求你不要向安讲那样的事。
③beg to do sth.有时可译作“请允许”。
- I beg to be allowed to say something about the plan.
我请求允许我谈谈这项计划。
④beg 也可跟从句，从句中用直陈语气，也可用虚拟语气。
- I beg that neither of you will say anything about it.
我请求你们两个都不要对此说什么。 - I begged that I (should/may) be allowed to take part.
我请求允许我参加。
＊还可说：beg(for) forgiveness/mercy/a light/a cigarette/a lift in one's car等。
(3) plead也可以表示“恳求，祈求”，其用法为：plead (with sb.) for sth.; plead with sb. to do sth.。
- He pleaded with the manager for another chance to show his worth.
他恳请经理再给他一次机会来展示他的价值。 - He pleaded with his son to be less trouble to his mother.
他恳求儿子少给他妈妈制造麻烦。 - The man pleaded for/begged for mercy.
那个人祈求别人的慈悲。
(4) ①ask可表示“请求，要求”，为普通用词。
- I asked him not to do it again．
我请求他不要再做这事。 - I came to ask you a great favor.
我来是想请你帮个大忙。 - He said that Mr. Anderson was asking to see me.
他说安德森先生要求见我。
②ask跟从句时，从句谓语多用虚拟语气。
- I asked that I (should) be allowed to see the mayor himself.
我要求允许我去见市长本人。
③ask for除可表示“要求得到，要求给予”等意思，也可表示“请求，乞求”。
- He's asked for an interview with the manager.
他请求面见经理本人。 - I had never known her ask/beg for pity before.
以前我从不知道她祈求过怜悯。
＊关于ask，另见“ask...”条目。
(5) implore表示“恳求，哀求”，其用法为：implore pardon/mercy, implore sb. for sth., implore sb. to do sth.。
- The prisoner implored the king for mercy.
这位囚犯恳求国王发慈悲。 - He implored his boss to let him go home to see his sick wife.
他祈求老板让他回家看看生病的妻子。
(6) ①require意思是“需要、依靠……而成功”。
- We require more help to complete the job.
我们需要更多的帮助来完成这项工作。 - Will you require anything further, Monsieur?
先生，你还需要什么？
②require还作“要求”解，含有“必须做到”的意味，可以人或事物作主语，后接：带不定式的复合结构；名词，代词；that从句(从句常用虚拟语气)。
- I require you to speak of this to no one.
我要求你不要向任何人说及此事。 - The border police required the traveler to unlock his luggage.
边境警察要求该旅客打开行李。 - All passengers are required to conscientiously show their tickets.
所有乘客被要求自觉出示他们的车票。 - We require extra help.
我们需要额外的帮助。 - The school rules require that all of us (should) take part in political studies on Thursday afternoon every other week.
学校规章要求我们每隔一周的周四下午参加政治学习。
③require of表示“对……的要求”。
- The criteria required of a professor to attain the annual post subsidy are too high.
对一个教授获得年度岗位津贴的标准要求有些太高了。 - All he requires of the class is that they be clean, punctual and submissive.
他对全班的要求是：他们要干净、守时和顺从。 - Repayment was required of the debtor in five months' time.
要求债务人五个月后还款。
