1.advice, advise.[b] advice 是不可数名词，a piece of advice，advise 是动词。 This is my advice to you.[b]I was advised to purchase an economical car. 2.affect, effect. [b]affect 是动词; 意为influence. effect可以是动词也可以是名词。动词effect意为cause to happen, 名词effect意为the result。 Smoking affects health.[b]I was deeply affected by the news.[b]What is the effect of the movement? 3.farther, further. [b]Farther 指距离; further 表示时间，程度和数量等概念。 Chicago is farther north than Fort Worth.[b]Call this number if you want to get further information. 4. in regard to, as regards, 或 regarding I am writing in regard to (or as regards, regarding) your letter of May 10. 5.in spite of, despite都是介词,后面不跟从句。 Despite the bad weather we enjoyed our holiday.[b]In spite of the rain, he didn't bring an umbrella with him. 6.percentage, percent.[b]percent跟在数字之后 A large percentage of my money is spent on food.[b]Almost fifty percent of the students attend the concert. 7.principal, principle.[b]Principal可作名词或形容词,意为chief official or main. Principle仅作名词,意为fundamental truth 。 In his research he followed basic scientific principles.[b]The principal side effect of decongestants is drowsiness.[b]The chairman pointed out his principal objections. 8.wait on意为serve, 不要与wait for混淆。 My friend was late; 1 had to wait for him for half an hour. [b]Good waiters are willing to wait on customers.