先参考一下正确与不正确的例句：
(O) Mary ate an apple and an orange.
玛丽吃了一个苹果和一个橘子。
(O) Mary always eats a piece of fruit in the afternoon.
玛丽总是在下午吃一个水果。
(O) Mary ate the apple and the orange in the refrigerator.
玛丽吃了放在冰箱里的苹果和橘子。
(X) Mary includes the apple in her daily diet.
玛丽在她的每天饮食中包括了这个苹果。
Correction:
Mary includes an apple in her daily diet.
更正：玛丽在她的每天饮食中包括了一个苹果。
(X) Joe stops at the corner Starbuck for the cup of coffee each morning.
每天早晨乔为了这被咖啡在拐角的星巴克的停留。
Correction:
Joe stops at the corner Starbucks for a cup of coffee each morning.
更正：每天早晨乔为了一杯咖啡在拐角的星巴克的停留。
(X) Brad and his friends like to try the different restaurant every weekend.
布莱德与他的朋友们喜欢每个周末尝试这个不同的餐厅。
Correction:
Brad and his friends like to try a different restaurant every weekend.
更正：布拉德和他的朋友们喜欢每到周末尝试一个不同的餐厅。
(X) Creative people are more productive in the quiet space.
创意性的人在这个安静的空间更有效率。
Correction:
Creative people are more productive in a quiet space.
更正：创意性的人在一个安静的空间更有效率。
(O) The family of four decided to go see a movie after they had dinner.
一家四口吃过晚饭后决定去看一部电影 。
(O) The family of four decided to go see the movie everyone is talking about.
一家四口吃过晚饭后决定去看大家都在讨论的那部电影 。
(O) Norah is always studying or working, and she hasn’t had time to watch a movie, or have a cup of coffee with a friend for months.
诺拉总是在读书或则或工作，而她几个月都没有时间去看一部电影或者与朋友喝一杯咖啡了。
(O) Norah hasn’t had time to go to the movies or visit the museums the entire semester.
诺拉整个学期都没有时间去看电影或者参观博物馆了。
(X) After Norah finished her finals, she went to see the movie with her friends, and enjoyed the nice dinner l together.
诺拉完成了期末考以后，与朋友去看了这部电影，并一起享受了这顿美好的晚餐。
Correction:
After Norah finished her finals, she went to see a movie with her friends, and they enjoyed a nice meal together.
更正：诺拉完成了期末考以后，与朋友去看了一部电影，并一起享受了一顿美好的晚餐。
Common idiomatic examples that display nonspecific references
通用俚语的示范不具体的例子：
An apple a day keeps the doctor away.
一天一苹果，医生远离我。
She is like a cat on a hot tin roof.
她就像一个热铁皮屋顶上的猫。
Examples with indefinite article 需要用不定冠词的例句：
An apple a day keeps the doctor away implies that a person should always remember to include an apple, or a piece of nutritious fruit in his or her daily diet.
「一天一苹果，医生远离我」意味着，一个人应该记住在他的日常饮食中包括一个苹果或一个营养的水果。
The phrase “like a cat on a hot tin roof” is used to describe a person who is in a state of unsettlingly anxiety, and is unable to hold still.
「像一个热铁皮屋顶上的猫」这句话是用来形容一个人焦虑不安的状态，而无法保持不动。
Examples with definite article 需要用定冠词的例句：
All apples are beneficial to your health, and you don’t have to go to the supermarket to find a specific apple. Unless you are Snow White’s evil stepmom, then you would want the princess to take a bite out of the poison apple, which you have specially prepared.
所有的苹果都对你的健康有益。你不需要去超市找任何特别的苹果。除非你是白雪公主的邪恶继母，那你就会期待公主咬一口你特制的毒苹果。
If the “cat on a hot tin roof” scenario is literal, then you can say: “My cat got out of the house, and climbed up onto roof, now it is jumping around because the roof of our house is really hot.”
如果「热铁皮屋顶上的猫」是真实的。你可以说：「我的猫跑出去，爬上了我们家的屋顶，因为我们的房子的屋顶很热，所以它现在跳来跳去」。
An “a” or an “an”? 到底是 “a” 还是 “an”？
基本上来讲，如果名词是母音开头，就用 “an”，其它的都是用 “a” 的原则很简单。可是 wait a second！这么简单的规则就不好玩了。参考以下的例句，看你会不会发现有什么不一样的地方？
It’s an honor to meet you.
很荣幸认识你。
The sign “Missisippi River” is missing an “s” in “Mississippi”.
「密西西比河」的标牌中的 “Missisippi” 缺少了一个 “s” 字母。
He made a U-turn.
他转了一个U型转弯。
Every high school senior wishes to get into a university.
每一位高中的四年级生都期望进入一所大学。
为什么 “a honor” 变成了 “an honor”，”a ‘s’” 是 “an ‘s’”, “an U-turn” 是 “a U-turn”， 还有好端端的 “an university” 变成了 “a university”？
再大声的读一次，答案马上就出现了：
It’s an honor to meet you.
• The “h” in the pronunciation of “honor” is silent.
• “honor” 的 “h” 是没有声音的。
The sign “Missisippi River” is missing an “s” in “Mississippi”.
• The alphabet “s” is pronounced as “es” [es].
• 英文字母 “s” 的发音是 “es” [es]。
He made a U-turn.
• The correct pronunciation of “U-turn” is “You turn” [yoo-turn]
• “U-turn” 正确的发音是 “You turn” [yoo-turn]。
The high school senior is worried that she might not get into a university.
“University” is pronounced as “you-ni-ver-si-ty” [yoo-nuh-vur-si-tee].
“University” 是发音成 you-ni-ver-si-ty” [yoo-nuh-vur-si-tee]。
区分一个字开头的音是否真的有母音的发音的好办法就是大声的念出来。也有更好的办法：查一下字典，仔细研究一下。如果自己练习时发觉 “a honor” 或者 “an university” 听起来不大对劲，你很可能是正确的。不要忘记，学英文时，不止是眼睛要注意的看，也要竖起耳朵，相信你的听力！
