## Lesson 15
### New words and expressions 生词和短语
1. customs n. 海关
- custom n. 风俗习惯
2. officer n. 官员
- office n. 办公室
3. girl n. 女孩，姑娘
- boy 男孩
- girlfriend 女朋友
- boyfriend 男朋友
4. Danish adj. & n. 丹麦的，丹麦人，丹麦语
- Denmark n. 丹麦
5. friend n. 朋友
> e.g. A friend in need is a friend indeed.患难见真情
- friendly adj. 友好的
- a friendly smile
6. Norwegian adj. & n. 挪威的，挪威人
- Norway n. 挪威
7. passport n. 护照
- pass v. 通过
- port n. 港口
- visa 签证
8. brown n. 棕色的
9. tourist n. 旅游者
- tour v. n. 旅行
> -ist 表示“人”的后缀
- artist 艺术家
- scientist 科学家
### 将课文中句子的复数变为单数
```
Are you Swedish?
No,I am not.
I am Danish.
Is your friend Danish,too?
No she isn't.
She is Norwegian.
Your passport,please.
Here it is.
Is this your case?
No it isn't.
My case is brown.
Here it is.
Are you a tourist?
Yes,i am.
Is your friend a tourist too?
Yes,she is.
That's fine.
Thank you very much.
```
### 名词变复数
英文中名词分可数名词和不可数名词，可数名词有单数和复数两种形式，指一个以上事物时用复数。
#### 如何区分可数不可数
- 最可靠的是查字典
- 一般来说有具体形状的事物是可数名词
- 没有固定形状的是不可数名词
#### 名词变复数规则：
1. 一般名词词尾加-s构成复数
```
e.g. friend-friends
case -cases
handbag-bandbags
umbrella-umbrellas
```
2. 以-s -x -ch -sh 和部分o结尾的词词尾加-es
```
e.g. dress-dresses
box-boxes
watch-watches
dish-dishes
tomato-tomatoes
potato-potatoes
photo-photos
```
3. 以辅音字母+y结尾的单词把y变i再加-es
```
e.g. baby-babies
city-cities
```
- 注意：以元音字母+y结尾的单词复数加-s
```
boy-boys
key-keys
```
4. 以-f,-fe结尾的单词把-f,-fe变为v再加-es
```
wife-wives
wolf-wolves
```
5. man,woman及以其结尾的名词把man变为men,woman变为women
```
policeman-policemen
policewoman-policewomen
```
6. 不规则名词复数需要单独记忆
```
tooth-teeth
child-childen
```
