初中英语常见错误之U系列　　under 　　[误] The lake is two meters under sea level.
　　[正] The lake is two meters below sea level.
　　[析] under的意思是在某物的下面，而below=lower than, 即低于。
　　[误] Under the help of our teacher, all of us passed the exam.
　　[正] With the help of our teacher, all of us passed the exam.
　　understand 　　[误] I think it is diffcult to make myself to understand.
　　[正] I think it is diffcult to make myself understood.
　　[析] 这句话的意思是我想让别人理解我太难了。
　　[误] I am understanding the lesson now.
　　[正] I understand the lesson now.
　　[析] understand一词没有进行时态。
类似的词还有belong, find, hear, love, like等。
　　until 　　[误] We walked until the edge of the forest.
　　[正] We walked as far as the edge of the forest.
　　[误] Our school bus can hold until twenty children.
　　[正] Our school bus can hold up to twenty children.
　　[析] until与till两词的意思一样，但两个词都只能用于时间，如： Ill wait until I hear from you.
　　[误] I waited for my mother to seven oclock, but she didnt come.
　　[正] I waited for my mother until seven oclock, but she didnt come.
　　[误] Can you return this book until Monday 　　[正] Can you return this book by Monday 　　[析] 当我们谈目前正在进行而将来某一时刻才停止的事件时用until，而用by来表达将来某一时刻会发生的动作。
　　[误] We arrived home until it became dark.
　　[正] We didnt arrived home until it became dark.
　　[析] until用于肯定句时表示某动作直到为止，如： They worked until 5∶00 P.
M.
用于否定句中时意为直到才。
所以用于肯定句中要遥延续遥动词，但截止遥动词却可以用在否定句中。
　　upstairs 　　[误] He went to upstairs.
　　[正] He went upstairs.
　　[析] upstairs一词可用作副词，如： We all hurried upstairs to see what happened.
也可用作名词，如; The upstairs of the house needs painting.
同时也可以用作形容词，如： A house with three upstairs rooms is quite good.
　　use 　　[误] It is no use to ask her.
　　[正] It is no use asking her.
　　[析] It is no use与There is no use后通常用动名词，而不用不定式。
　　[误] Ill get used to treat the students this way.
　　[正] Ill get used to treating the students this way.
　　[析] be used to与get used to后要接动名词表示习惯于做某事。
　　[误] I used to getting up early in the morning.
　　[正] I used to get up early in the morning.
　　[析] used to表示过去习惯的动作，其后要加动词原形。
　　[误] Oil was used to cooking.
　　[正] Oil was used to cook.
　　[析] 这里的句型虽然也是be used to但这里不是主动态，而是被动态，所以不能接动名词而应接不定式。
　　[误] We used to go to the Great Wall three times.
　　[正] We went to the Great Wall three times.
　　[析] used to只能用来表示一种习惯，而不能用来表达某事发生的次数。