The dress fits me well,I don’t want to buy it because it’s t

应该用and,不能用but
下面举例说明
某省高考题中有这样一道选择题：I hope you don’t mind me asking,_____ where did you buy those shoes?A.so B.and C.yet D.but
该题的正确答案应选D,但是不少学生选错了,因为他们习惯地认为but是表转折的.这是由思维定势引起的误解.下面就几例易产生误解的词或词组作简要说明,以防学生再犯类似错误.
一、But并不表转折,而and可表转折.
1.I don’t know you,but who are you?我不认识你,（那么/而）你（到底）是谁呢?
2.I’m sorry,but I can’t agree.很遗憾,我无法赞同.
3.But now to the main subject.那么现在进入正题吧.
4.“He’s won the race.” “But that’s terrific.” “他跑了第一.”“哇,那太棒了.”
其实,but习惯用于英语口语中,表轻微的转折、话题的改变或惊叹,可根据上下文意译或不译.上面的那道高考题就属于此类用法.而and在句中倒可以表转折,引导对比性的内容,意为“尽管如此”“不过”“但是”,可看作是and yet对yet的省略,如：He is very rich,and he lives a simple life.尽管他很富,但却过着简朴的生活.
二、now表过去,而then表将来.
1.He was now eighteen years old.他那时18岁.
2.The war was now over.当时战争已经结束了.（这两句中的now同then.）
3.If you’re coming tomorrow,I’ll tell you in detail then.如果你明天来,那时我会告诉你详情.
三、too...to表肯定.
我们所见的too...to的结构常常是表达否定的含义,如：The child is too young to go to school.这孩子太小还不能上学.但在下列句子中都表达的是肯定的含义.
1.You can’t be too careful to drive.你开车越小心越好.
2.They were too anxious to go home on Sundays.每到星期天他们都急着回家.
3.I’m only too glad to help you.我非常高兴地帮助你.
否定词与too...to的结构连用和too接anxious,eager,glad等少量形容词时都表达肯定的含义.
四、since表“自从……结束以来”
since所表达的意义常常是指“自从……开始以来”,如：I have never heard from him since he went to America.自从他去了美国我从未收到过他的信.如果按照这个思维定势来做下列选择题则往往出错.
------It has been five years since I learn English.
------_______!Can you tell me some reasons?
A.Great B.Congratulations C.Wonderful D.What a pity
本题的正确答案为D,正是考查对since的理解,是指“自从……结束以来”,意为“我已经五年没学英语了.”如果since后接瞬间性动词,意为“自从……开始以来”,如将上句改为It has been five years since I began to learn English.有了瞬间动词begin ,则意为“我学英语已有五年了”；如果since后接延续性动词,则表示“自从……结束以来”,又如It has been two months since he smoked.smoke 为延续性动词,所以意为“他戒烟两个月了（两个月没吸烟了）”.
同学们在做题时一定要根据上下文正确地理解题意,不可凭思维定势来答题.