A colon usually indicates a pause after a cue or suggestion, or indicates a hint for the following context or summarizes the anterior context.
A colon is used in the following cases:
Used after the general or suggestive words to prompt for the following context 用于总说性或提示性词语后
北京紫禁城有四座城门：武门、神武门、东华门、西华门。The Forbidden City in Beijing has four gates: Wu gate, north gate, Donghua gate, Xihua gate.
她高兴地说：“我们去好好庆祝一下吧”。She said happily, “let’s go and celebrate”.
Used to summarize the above-mentioned points 用于总结上文
张华考上了北京大学；李萍进了中等技术学校；我在百货公司当售货员：我们都有光明的前途。Zhang Hua admitted to Peking University; Li Pingjin went to a secondary technical school; I worked as a shop assistant in a department store: we all have a bright future.
Used after the words that need to be explained, introducing further details o explanations 用于需要解释的词语后边，表示引出解释或说明。
After the address forms of a letter or speech. 用在书信、讲话稿中称谓语或称呼语之后。
同志们，朋友们：现在开会了……Comrades, friends: We are meeting now.
A colon can not be used in a sentence in which there is already one. If the second colon is necessary, a new sentence must be made.
The comma in Chinese is the most frequently used punctuation mark. Furthermore, it’s also the most difficult to use among all the punctuation marks in Chinese.
A comma indicates a general pause interval in a sentence and it divides a sentence into meaning groups. In Chinese, a comma is used in the following cases:
When a pause between a subject and a predicate is needed within a sentence 当句中的主语和谓语之间需要停顿时
这所学校的学生，大部分是外国学生。Most of the students in this school are foreign students.
我昨天晚上吃的晚餐，一点都不好吃。The dinner I had last night was not good at all.
When a pause between the verb and the object is needed within the sentence 当句中的谓语和宾语之间需要停顿时
后来我才知道，他对我说的话是假话。I just knew later that what the told me was a lie.
你要知道，想考入这所大学需要付出很多努力。You know, it takes a lot of effort to get into this university.
When a pause after the adverbial at the beginning of the sentence is needed 句首的状语之后
对于这位教授，她并不陌生。She is no stranger to the professor.
关于那件事情，他有自己的观点。On that matter, he has his own point of view.
For a pause between the clauses within a complex sentence, a comma must be used besides the semicolon 复句内各分句之间的停顿，除了有时要用分号外，都要用逗号
要是不相信我们的理论能反映现实，要是不相信我们的世界有内在和谐，那就不可能有科学。If we do not believe that our theory can reflect the reality, if we do not believe that our world has inner harmony, there can be no science.
Used after a long subject 用在较长的主语后
苏州园林建筑各种门窗的精美设计和碉楼功夫，都让人叹为观止。The exquisite design and engraving of a variety of doors and windows of the architecture of The Classical Gardens of Suzhou are really stunning.
Used before a long object 用在较长的宾语前
许多学者认为，这些在中国南方刚出土的文物可以追溯到几千年前。Many scholars believe that these relics newly unearthed in southern China can be traced back thousands of years ago.
Between several long subjects 用在较长的主语之间
Mother’s painful telling, as well as the fact she witnessed, have inspired the idea of pursuing the truth in my childhood.
Between several long predicates 用在较长的谓语之间
那姑娘头戴草帽，身穿一定绿色的裙子，腰间还系者一跟红色的腰带。（戴, 穿 and系 are three predicates）The girl wears a straw hat, a green dress, and also a red waist belt.
Between several long objects 用在较长的宾语之间
必须懂得，对于文化传统，既不能不分青红皂白统统抛弃，也不能不管精华糟粕全盘继承。We must understand that, for cultural traditions, we can not indiscriminately abandon all, neither can we inherit overall, essence or dross.
After a prepositive predicate 用在前置的谓语之后
真高啊，上海的金茂大厦。Really high, Shanghai Jinmao Tower.
Before a postpositive adverbial 用在后置的状语之前
他吃力地站了起来，慢慢地。He struggled to stand up, slowly.
Before a postpositive attribute 用在后置的定语之前
我只是一个人，孤孤单单的。I’m just a man, alone.
Used after the modal particle if there is any within the sentence 用在句内语气词之后
他呢，倒是很乐意地，全神贯注地干起来了。He, however, was glad to be absorbed in the work.
Used between the coordinate elements with modal particles 用在句内带语气词的并列成分之间
八月的大街上摆满了水果，像甜瓜啊，西瓜啊，苹果啊，葡萄啊……The streets of August are filled with fruits like melons, watermelons, apples, grapes …
Used between double-reference elements or parentheses 用在复指成分或插说成分之后
王明，我的小学同学，高中毕业后就出国了。Wang Ming, my primary school classmate, went abroad after graduating from high school.
他，不用说，一定又买彩票了。He, needless to say, must have bought a lottery ticket.
Used after an exclamation, appellation or address with moderated tone. 语气缓和的感叹语，称谓语，或呼唤语之后。
哎呦，疼死我了，快给我看看。Oh, it hurts me, give me a quick look.
大爷，您需要帮助吗？Grandpa, do you need help?
喂，您是哪位？Hello, who are you?
Used after words of sequence 用在次序语之后
In a word, a comma is used between the meaning groups within a sentence. A comma indicates a pause less than a semicolon greater than a comma.
The punctuation mark 句号 “。” a full stop or a period is adopted at the end of a sentence. So, in which cases we use a period in Chinese?
A period is used mostly in declarative sentences, but sometimes it can be also used in imperative sentences that don’t express very strong feelings or intense emotions.
1. At the end of declarative sentences 陈述句句末
At the end of a simple sentence 简单句句末
我是中国人。Wǒ shì zhōng guó rén。I’m Chinese.
我住在深圳。Wǒ zhù zài shēn zhèn。I live in Shenzhen.
他老婆是上海人。Tā lǎo pó shì shàng hǎi。rénHis wife is shanghainese.
At the end of a sentence without subject 无人称句句末
下雨了。Xià yǔ le。It’s raining。
世上无难事，只怕有心人。Shì shàng wú nán shì, zhǐ pà yǒu xīn rén。 Nothing in the world is difficult for one who sets his mind on it.
At the end of an elliptical sentence 省略句句末
几个人？十个。How many people? Ten.
谁迟到了？她。Who is late? She.
At the end of a complex sentence 复句句末
我昨天碰到了和我一起住过五年的室友。Wǒ zuó tiān pèng dào le hé wǒ yī qǐ zhù guò wǔ nián de shì you。I met my roommate who lived with me for five years.
如果明天下雨，我们就要取消计划。Rú guǒ míng tiān xià yǔ, wǒ men jiù yào qǔ xiāo jì huà。If it rains tomorrow, we will cancel the plan.
2. At the end of imperative sentences 祈使句句末
At the end of an imperative sentence with a soothing tone 气舒缓的祈使句末尾
请您稍等片刻。Qǐng nín shāo děng piàn kè。Please wait a moment.
请您尽快跟我们联系。Qǐng nín jǐn kuài gēn wǒ men lián xì。Please contact us as soon as possible.
At the end of an imperative sentence for general prohibitions and requirements 表示一般禁止和要求的祈使句句末
请勿乱扔垃圾。Qǐng wù luàn rēng lā jī. Please don’t litter.
今日事今日毕。Jīn rì shì jīn rì bì。 Don’t put off till tomorrow what should be done today.
If an imperative sentence express very strong feelings or emotions, an exclamation mark have to be used.
To sum up, 句号 a period (or a full stop) is an ending signal of a sentence especially declarative sentence, and indicates a complete expression.
Credit: Decode Mandarin Chinese