Not "They buys their clothes here." — say "They buy their clothes here.". 这里不用加 -s；-s 只有 he、she、it 才用。
试一试: We ___ at Mosh Market. (work / works) 答案: work — 如果你加了 -s（"works"），那个词尾只用于 he/she/it。用 we 的时候，动词要保持原形：We work at Mosh Market.
don't + 动词
用 I, you, we, they 的时候，要说“不”，就在动词前面加 don't。don't 后面的动词用原形。
I don't live here.
You don't work at home.
They don't wear a jacket. It is very hot.
Not "I no live here." — say "I don't live here.". 英语要把 don't 放在动词前面。光用 no 是不行的。
试一试: We ___ in Haffenville. We live in Senfarrow Brook. (don't live / not live / don't living) 答案: don't live — 用 we 的时候，否定就是 don't 加动词原形：don't live。not live 前面没有 don't；don't living 把动词的形式改了，可 don't 后面的动词要保持原形。
Do you...? 和简短回答
用 I, you, we, they 问别人做不做某个动作时，先说 Do，再说人，最后是动词原形。回答可以很简短：Yes, I do. 或 No, I don't.
Do you live here? Yes, I do.
Do they work at home? No, they don't.
Do we pay now? Yes, we do.
Not "Do you live here? Yes, I live." — say "Do you live here? Yes, I do.". 简短回答里要用回 do，不是重复问句里的动词。
试一试: Maya: Do you buy your shoes here? Lars: ___ I buy all my clothes at Mosh Market. 选出 Lars 的简短回答。 (Yes, I do. / Yes, I buy. / Yes, I am.) 答案: Yes, I do. — 以 Do 开头的问句，回答时要用回 do：Yes, I do. Yes, I buy. 是把动词又重复了一遍，而 Yes, I am. 回答的是以 Are 开头的问句。
go to 某个地方，go home
go 后面接地点时要加 to：go to work、go to school、go to the market。在 home 前面不加 to：go home。
I go to work.
We go to the market and buy bread.
They go home and eat.
Not "They go to home and eat." — say "They go home and eat.". 这四个里面，只有 home 前面不加 to。
试一试: I work at Mosh Market. Then I ___ and eat with my family. (go home / go to home / go the home) 答案: go home — home 就是那个不加 to 的说法：go home。go to home 把这个说法本来省掉的 to 又加回去了，而 go the home 英语里根本不这么说。
Are you...? 还是 Do you...?
看人后面的那个词。如果是描述的词、人或者东西，就用 Are you...?；如果是动作，就用 Do you...?
Are you cold? (cold is a describing word)
Are you Mei's sister? (a sister is a person)
Do you live here? (live is an action)
Not "Are you live here?" — say "Do you live here?". live 是动作，所以问句要以 Do 开头，不是 Are。
试一试: ___ you buy your clothes here? (Do / Are / Is) 答案: Do — buy 是动作，所以问句以 Do 开头。Are 用来问描述的词或者东西，而 Is 从来不跟 you 一起用。
试一试: ___ you cold in that T-shirt? (Are / Do / Have) 答案: Are — cold 是描述的词，不是动作，所以问句以 Are 开头。Do 用来问动作，而问描述的词时也不能用 Have。
什么时候用
这个形式用来说 习惯、事实 或 日常行为：一次又一次都成立的事情，不只是此刻。
I drink tea every morning. (routine)
Water is cold in winter. (fact)
We go to the market on Saturday. (habit)
试一试: 一句说的是 Amina 和 Mei 反复做的 习惯，一句说的是关于世界的 事实。哪一句是习惯？ (Amina and Mei walk to class every day. / Haffenville has two parks.) 答案: Amina and Mei walk to class every day. — every day 说明她们一直在重复，所以是习惯。而“Haffenville has two parks”是事实：它本来就是这样，不是谁一次又一次做的事。一般现在时两种都能表示。