说到一样东西之前，我们常常会说 a 或 the。a = 很多当中的一个，新提到的 · the = 我们俩都知道是哪一个。
a 还是 the
Lani has a dog. The dog is small.
There is a cafe here. The cafe is very busy.
Look at the sun!
Not "Lani has the dog. (which dog? we don't know yet)" — say "Lani has a dog. (one of many, a new one)". a = 很多当中的一个，新提到的 · the = 我们俩都知道是哪一个。
Lani has a dog. The dog is small.
There is a cafe here. The cafe is very busy.
Look at the sun!
a dog — one of many, any dog, a new one
the dog — you both know which one
第一次说到它
第一次说到一样新东西时，用 a 通常最自然。之后再提到它，就用 the 指回去。
Ethan has a blue bag.
The bag is very big.
There is a new pool here. The pool is warm.
Not "It is the first time. "There is the pool here." (but we don't know which pool yet)" — say "It is the first time. "There is a pool here." (a new one, one of many)". 新东西、第一次 → a。已经知道是哪个 → the。
试一试: Lars："What is this?" Sofia："It is ___ phone. It is not my phone." 这里用哪个词？ (a / the) 答案: a — Lars 是第一次看到它，所以是 a phone。"The phone" 会让人以为你们俩已经知道是哪一部了。
我们都知道的那一个
你和对方都知道是哪一个，就用 the——就是眼前这一个，这个房间里、这个地方的那一个。
The door is open.
The pool is next to the gym.
Lani is at the cafe.
Not "There is one door here. "A door is open."" — say "There is one door here. "The door is open."". 我们都知道是哪个 → the。
试一试: Sofia 和 Lars 在一间办公室里，办公室只有一扇窗。Lars 说："___ window is open." 哪个词合适？ (The / A) 答案: The — 这间办公室只有一扇窗，你们俩都知道是哪一扇，所以用 the。"A window" 是很多扇当中的一扇。
只有一个
我们大家看到的都是同一个 sun、同一个 moon、同一个 sky。所以我们说 the sun、the moon、the sky。
The sun is very bright.
The moon is white tonight.
The sky is blue.
Not "A sun is very bright." — say "The sun is very bright.". 世上只有一个 → the。
试一试: Sofia："Look up, Lars!" Lars："Wow! ___ moon is very big tonight." 哪个词合适？ (The / A) 答案: The — 大家抬头看到的都是同一个月亮，所以是 the moon。"A moon" 会变成很多个月亮当中的一个。
常见错误有哪些？
错误
正确
原因
Lani has the dog. (which dog? we don't know yet)
Lani has a dog. (one of many, a new one)
a = 很多当中的一个，新提到的 · the = 我们俩都知道是哪一个。
It is the first time. "There is the pool here." (but we don't know which pool yet)
It is the first time. "There is a pool here." (a new one, one of many)