英语表示自然界某些独一无于的事物（如sun, moon, sky等）通常不可数，一般不连用不定冠词，而是习惯上连用定冠词。如：
The sun rose above the sea. 太阳升出海面。
It is no longer a dream to fly to the moon. 飞往月球已不再是梦想了。
A balloon floated across the sky. 有个气球从空中飘过。
但是，当它们受到描绘性形容词的修饰时，如果不是特指，则其前要用不定冠词，此时的a含有 a kind of 的意思。如：
A cloudy sky is not always a sign of rain. 阴天不一定是下雨的预兆)。
Day broke and a brilliant sun lit up the room. 天亮了，灿烂的阳光照亮了房间。
另外，当sun表示“星体”“恒星”时，它是可数的；当moon表示“卫星”时，也是可数的。
单词：sun的近义词、反义词、形近词辨析
fun/funny/sun/sunny/solar/gun/run/joy/pleasure/delight
记忆：
1. fun [ fQn ] n. 娱乐, 玩笑, 嬉笑, 有趣 (不可数名词) What fun it is to ride and sing a sleighing song tonight!今晚坐着雪橇唱着歌，我们真快乐。 for/in fun 开玩笑, 不是认真的
2. funny [ 5fQni] adj. 有趣的, 好笑的, 滑稽的, 古怪的 Have you ever met the funny-dressed man?你遇到这个穿着滑稽的人了吗？
3. sun [ sQn ] n. 太阳 The sun is the nearest star to the earth.太阳是离地球最近的恒星。
4. solar [ 5sEulE ] adj. 太阳的 Scientists are trying to find signs of life on another planet in the solar system.科学家们正设法在太阳系里的另一颗行星上寻找生命存在的迹象。
5. sunny [ 5sQni ] n. 晴朗的 Sunny weather is often preferred.人们常更喜欢晴朗的天气。
6. gun [ ^Qn ] n. 炮, 枪 In the 19th century the Ally of Eight Countries knocked China open with their guns.在19世纪八国联军用枪炮撞开了中国的大门。
7. run [ rQn ] vi. 跑, , 蔓延, 消褪，进行, 行驶 vt. 管理, 运行, 开动 Jim runs a successful chain shop.杰姆成功地经营着一家连锁店。 run for竞选 run after 追赶 run into 偶遇
8. joy [ dVCi] n. 喜悦, 快乐, 乐事, 乐趣 To our joy, the boy behaved himself at the dinner party.令我们高兴的是，这男孩在宴会上表现很好。 to one’s joy, 令某人高兴的是
9. pleasure [ 5pleVE] please, 使愉快；pleasure, n.愉快, 快乐, 乐事 It’s a pleasure to stay with you.和你在一起是件愉快的事。 格言： Business before pleasure.事业在先，享乐在后。
10. delight [ di5lait ] de-, 使；light,轻松的；delight, 使轻松，n. 快乐, 高兴, 喜悦 v. (使)高兴 We are delighted to have such a chance. 我们很高兴有这样的机会。
另类阅读：
Have fun in the sun! You see, it’s a nice and sunny spring day. Come out and delight yourself! There are pleasures waiting for you. Run and find the gun. Don’t worry; it’s just a funny toy gun!
与单词：sun 相关的例句或者名人名言
At dawn, the sun rises over the mountain.
早上，太阳升过山头。
She is lying in the sun with bare foot.
她光着脚躺在阳光下。
The sun is going down.
太阳逐渐落山了。
The forest looked beautiful when the sun shone through the trees.
当阳光穿过树木照下，整个森林看起来美极了。
In the winter the sun sets early.
冬天太阳下山早。
※For age and want save while you may; no morning sun lasts a whole day. 为了年老和急须，要及时积蓄，因为早晨的太阳，不会整天照耀。
※There are painters who transform the sun to a yellow spot, but there are others who with the help of their art and their intelligence, transform a yellow spot into the sun.Picasso, Spanish painter—— 有些画家把太阳画成一个黄斑，但有些画家借助于他们的技巧和智慧把黄斑画成太阳。西班牙画家 毕加索
※Let not the sun go down upon thy wrath. 日落之前，平息你的怒火吧。
※For age and want,save while you may! No burning sun lasts a whole day. 幼时防老，有时防无；朝阳虽好，难以终日。
