[误]This building is an university.
[正]This building is a university.
[析]a用于以辅音音素开始的单词前，而an用于以元音音素开始的单词前，而不是元音字母开头的单词前。university的第一个音素是[j]，所以 用a而不要用an。又如：There is a “n” in the word.是错句，应为：There is an “n”in the word.因字母n的发音的第一个音素是元音。要注意的还有hour因其第一个字母h不发音，所以应该用an hour。例如：
I need an hour to finish the work.
It is a useful dictionary.
It is a European country.
I bought a used car.
[误]I need a umbrella because it looks like raining.
[正]I need an umbrella because it looks like raining.
[析]因umbrella的第一个音素是元音，所以应用an.常用的情况有：an old man, an English teacher, an elephant, an idea, an hour ago, an honest boy…。
[误]“Can you help me” “Sorry, I'm in hurry.”
[正]“Can you help me” “Sorry. I'm in a hurry.”
1. 用来表示一类人或事物，如：She is a teacher.
2. 指某一类人或事物中的一个，如：An elephant is bigger than a horse.
3. 泛指某一人或事物，如：A man is waiting for you at the school gate.
4. 相当于“one”的概念，如：I just bought a new dictionary.
如：have a walk/a rest /a look
又如：in a hurry 匆匆忙忙
make a face 作鬼脸
do somebody a favour 帮某人忙
a number of =many
又如：have a good time (玩得好)
have a cold (感冒)
have a headache (头痛)
have a break=have a rest
[误]I bought the dictionary yesterday. A dictionary is very good.
[正]I bought a dictionary yesterday. The dictionary is very good.
[误]Please turn off lights before you leave.
[正]Please turn off the lights before you leave.
[误]There are nine planets around a sun.
[正]There are nine planets around the sun.
[析]世上独一无二的天体等名词前应加定冠词，如：the earth, the moon, the sun, the sky, the sea.
[误]I live on a second floor of this building.
[正]I live on the second floor of this building.
[析]在序数词，形容词最高级前要用定冠词。如：He is the oldest in the family.
[误]I want to learn the second language this term.
[正]I want to learn a second language this term.
[误]Mississippi is one of the longest rivers in the world.
[正]The Mississippi is one of the longest rivers in the world.
[析]在河流名称前应加定冠词，如：the Yellow River(黄河)。
[误]Look, there are Alp.
[误]Look, there are the Alp.
[正]Look, there are the Alps.
[析]具体的某一座山不加定冠词，如：Mountain Tai.但在山名称前加定冠词后，其山名要加s，来表示山脉。the Alps即为阿尔卑斯山脉。如:The Alps are in the center of Europe.
[误]Times is one of the oldest newspapers in the world.
[正]The Times is one of the oldest newspapers in the world.
[误]Rich are not always happy.
[正]The rich are not always happy.
[析]在形容词前加定冠词表示一类人，而在姓的前面加定冠词，姓后加s表示某一家，如：The turners are going to move to New York.
[误]I like to eat bread for breakfast. Bread sells in this shop is very good.
[正]I like to eat bread for breakfast. The bread sells in this shop is very good.
[误]The sun rises in east.
[正]The sun rises in the east.
[析]在方向、方位前应用定冠词，如：in the east, in the west, in the north, in the south, in the direction 及in the past, in the future
[误]Do you know who invented telephone
[正]Do you know who invented the telephone
如：the English Channel 英吉利海峡
the Panama Canal 巴拿马运河
the Suez Canal 苏伊士运河
[误]Would you please buy some food for the supper
[正]Would you please buy some food for supper
[误]I like to climb the mountain in the autumn.
[正]I like to climb the mountain in autumn.
[析]一年四季前不用定冠词，如：Spring is the best season in a year.
[误]Sometimes my parents come to school to see me.
[正]Sometimes my parents come to the school to see me.
[析]有些名词被用作其本身原来所含目的时不加冠词，如：go to school上学，leave school(辍学)，after school(放学)，但如果当建筑物讲时应加冠词，如例句中其父母来校不是上学，而是看望孩子，则要加定冠词。又如，He was in hospital for two days.(他在医院住院两天了。)而：He went to the hospital to see his mother.他去医院看望他的母亲。
[误]I bought a same dictionary as she bought.
[正]I bought the same dictionary as she bought.
[析]在惯用法the same, the only, the very前的定冠词不可换为不定冠词。
[误]The police caught the thief by his arm.
[正]The police caught the thief by the arm.
[析]这是英文表达法与中文的明显不同之处，也是初学者极易忽视之处。在英语中的某些动词，如：catch(抓)，take(拿)，strike (打),pat(拍)，hit(击)，hold(握)，pull(拉)…动词后应加人，再加介词on, by, in, with…之后要加定冠词，再加人体的某一部位。这时的定冠词千万不要换作his, her, their, 等词。
[误]He was paid by hour.
[正]He was paid by the hour.
[误]I went to New York by his car.
[正]I went to New York by car.
[正]I went to New York in his car.
[析]by仅仅与交通工具相连表示应用某种工具，而加了别的修饰词后其前面的介词也应作相应的转换。如：by car (坐小汽车)by taxi (坐出租车)by bike (骑自行车)by water (乘船)by air (乘飞机)by sea (乘船)
[误]Mary began to learn how to play piano when she was three.
[正]Mary began to learn how to play the piano when she was three.
[析]在乐器前要加定冠词，而在球类游戏之前则不要加冠词，如：They like to play bridge when they are free. (他们空闲时爱打桥牌)
[误]The little boy wanted to go to cinema.
[正]The little boy wanted to go to the cinema.
[析]英语中虽有一些名词与go to连用时不加定冠词，以表示该名词的内涵，如：go to school (上学)，go to bed(睡觉)等，但去看电影则例外，要用go to the cinema.这也是语言的一个特点。
[误]I live at 105 the Lake street.
[正]I live at 105 Lake Street.
[误]Next summer holiday I will go to country to live on a farm.
[正]Next summer holiday I will go to the country to live on a farm.
[析]country既作国家讲也作乡村讲。作乡村讲时，一定要加定冠词，而且只有单数形式，作国家讲时则可有复数形式。如：Japan is a country .Japan, China, India are Asian countries.
[误]The picture looks better at the distance.
[正]The picture looks better at a distance.
[析]at a distance意为“离开一定距离”。而in the distance为“远方，远处”。这样常用的词组有：
as a rule (照例)
in a hurry (匆忙)
in the morning/afternoon (上/下午)
in the sun (在阳光下)
in the rain (雨中)
in the same way (同样)
in the shade (在阴凉处)
in the day time (白天)
in the end (最终)
on the other hand (换句话说)
on the contrary (相反)
[误]The little boy and girl walk along the street a hand in a hand.
[正]The little boy and girl walk along the street hand in hand.
bit by bit (逐渐)
day after (by) day (一天又一天)
day and night (日日夜夜)
face to face (面对面)
from A to Z (自始至终)
from time to time (再三)
hand in hand (手拉手)
shoulder by shoulder (肩并肩)
1 Mr Li is___ old worker.
A a B an C some D /
2 English is___ useful language in ___ world.
A an, the B a, the C the, / D /,the
3 What ___ interesting book it is?
A a B an C the D /
4 He will be back in ___ hour.
A / B the C a D an
5 There is ___ map in the classroom. ___ map is on the wall.
A a, A B the, The C a, The D the ,A
6 Look at___ picture! There's___ house in it.
A a ,a B the, the C a, the D the, a
7 There is ___ orange in the bottle.
A a B an C the D /
8 Beijing is ___ capital of our country.
A the B an C / D a
9 If you work hard at English, you'll get ___ “A” in the test.
A an B / C the D a
10 He usually goes to school on ___ foot.
A a B an C the D /