Auxiliary verb "yao" and its multiple meanings
You probably already know the basic meaning of 要 (yào) as "to want." It is actually a quite versatile word, though, and can also take on the meanings of "to need" as well as "will (do something)." In every case, context is crucial for figuring out which meaning someone is trying to express.
要 as "want"
This structure could be used when ordering food at a restaurant or a shop. Here, it's being used for saying that you want something.
Subject + 要 + Noun
- 我 要 一 杯 水 。 I want a cup of water.
- 我 要 一 份 牛排 。 I want a steak.
- 我 要 一 杯 咖啡 。 I want a cup of coffee.
- 我 要 一 个 面包 。 I want bread.
- 我 要 冰 的 可乐 。 I want coke with ice.
- 你 要 热 牛奶 吗 ？ Do you want warm milk?
- 我 要 一点 糖 。 I want some sweets.
- 我 要 两 份 鸡 肉 。 I want two pieces of Chicken.
- 我 要 法国 红 酒 。 I want French wine.
- 我 要 苹果 汁 。 I want apple juice.
要 as "want to"
In Chinese, 要 (yào) can mean "want to" (similar to 想 (xiǎng)), but its tone is quite firm. So it's used for saying that you want to do something.
Subject + 要 + Verb
- 我 要 吃 巧克力 。 I want to eat chocolate.
- 我 要 跟 你 一起 去 。 I want to go with you.
- 我 要 吃 西餐 。 I want to eat western food.
- 我 要 学 中文 。 I want to study Chinese.
- 我 要 去 泰国 。 I want to go to Thailand.
- 我 要 买 一 个 新 手机 。 I want to buy a new cell phone.
- 我 要 工作 。 I want to work.
- 我 要 打 电话 。 I want to make a phone call.
- 我 要 见 他 。 I want to see him.
- 我 要 试 一下 。 I want to try.
要 as "need to"
If you crank the urgency of "to want" up a few notches, you get "to need." The two meanings overlap, creating a fuzzy, "needy" gray area.
Subject + 要 + Verb
- 明天 我们 要 上班 。 (logically, most people don't really WANT to work) We need to work tomorrow.
- 你 要 现在 付钱 。 (No one WANTS to pay, right?) You need to pay now.
- 我们 要 买 很 多 酒 。 We need to buy a lot of wine.
- 我 要 休息 一 下 。 We need to rest for a while.
- 你 要 找 一 个 中文 老师 。 You need to find a Chinese teacher.
- 今天 很 忙 ， 我 要 加班 。 Today is very busy, so I need to work overtime.
- 你 要 多 吃 点 水果 。 You need to eat a lot of fruit.
- 你 要 学 会 用 电脑 。 You need to use the computer while you study.
- 明天 下雨 ， 你 要 带 雨伞 。 It will rain tomorrow, you need to bring an umbrella.
要 as "going to"
This use of 要 (yào) is like "going to" (similar to 会 (huì)).
Again, no change to the structure here, but it often includes a mention of a time when something is going to happen.
Subject + 要 + Verb
If you want to know more about the related pattern "要...了" (yào... le), please see about to happen with "kuai... le".
- 明年 我 要 去 中国 。 (Notice the use of a time word for the future) Next year I am going to go to China.
- 明天 我 要 去 北京 。 (This could also mean "need," depending on context) I am going to go to Beijing tomorrow.
- 星期五 我们 要 开会 。 We are going to have a meeting on friday.
- 12 点 我 要 去 吃饭 。 I am going to go out and eat at 12 o'clock.
- 2014年 ， 我 要 去 中国 工作 。 In 2014 I am going to go to China to work.
- 一会儿 我 要 出去 。 I am going to leave soon.
- 我 要 认识 很 多 中国 朋友 。 I am going to get to know lots of Chinese friends.
- 我 要 做 咖啡 ， 你 喝 吗 ？ I am going so make some coffee, do you want some?
- 我 要 找 新 的 工作 。 I am going to find a new job.
- 我 要 每天 运动 。 I need to exercise every day.
Context, context, context
You may have noticed that the meanings can easily overlap. To figure out what is intended, you need to use context. How urgent is the situation? Is it likely to be something the speaker really wants to do? Is it something that's totally going to happen, regardless of anyone's preferences? Most often, a little background knowledge and some common sense are all you need to figure it out. With that said, you definitely need to be aware of the different possible meanings listed above.