Unit 12
Vocabulary
stagnant
停滞的、不流动的（一潭死水，水不流动就叫 stagnant）
The stagnant water in the pond smelled bad.
Mosquitoes breed in stagnant water.
breed
繁殖；饲养（breed 的过去式和过去分词都是 bred）
Rabbits breed very quickly.
The farmer breeds chickens and ducks.
Grammar
第三人称单数（动词 +s/es）
He / She / It / 单数名词 + 动词s/es
一般现在时，主语是第三人称单数时，动词要加 s 或 es
She likes apples. He goes to school every day.
第三人称单数 — 加 es 的情况
以 s/x/ch/sh/o 结尾的动词 + es
go→goes，do→does，watch→watches，wash→washes
He watches TV every night. She does her homework.
第三人称单数 — y 变 ies
辅音字母 + y 结尾的动词，变 y 为 ies
study→studies，fly→flies，cry→cries
He studies English every day. The baby cries at night.
have 的第三人称单数是 has
I/you/we/they + have，he/she/it + has
I have a book. She has a book.
第三人称单数否定句
He/She/It + does not + 动词原形
用 does not（doesn't），后面动词要用原形
He does not like apples. She does not play football.
第三人称单数疑问句
Does + he/she/it + 动词原形？
用 Does，后面动词用原形（不加 s）
Does she like milk? Does he go to school by bus?
过去完成时（Past Perfect）
had + 过去分词
表示在过去某时间之前已经完成的事，先发生的用 had + 过去分词
She had finished her homework before dinner.
过去完成时 — 常用时间词
before / after / already / when / by the time
这些词常和过去完成时一起出现
By the time I got home, my mother had cooked dinner.
被动句（Passive Voice）
be 动词 + 过去分词
表示某人或物"被……"，一般过去时用 was/were
The window was broken by the boy.
主动句变被动句
把宾语移到主语位置 + be动词(时态对应) + 过去分词 + by + 原主语
The cat ate the fish → The fish was eaten by the cat.
The car was washed by my father.
Easily Confused
He likes
Does he like
肯定句，动词加 s
疑问句，Does 后面动词用原形
He likes apples.
Does he like apples?
过去完成时 had done
一般过去时 did
两个过去的事中，先发生的那个用 had done
直接说过去发生的事情
She had left before I arrived.
She left at 3pm.