I bought bread, cheese, and pickles at the grocery store.
Astronomers have known about the positions of stars for centuries, but they didn’t understand that the earth revolves around the sun.
In preparation for the next convention, the representatives studied up on the most important issues.
All doctors, if they care about their patients, are concerned with good office hygiene.
Comma splice 不要在未使用连接词的情况下，使用逗号分隔两个独立的从句
错误范例： Thousands of protesters showed up on the streets, they were shouting and carrying large posters.
正确范例： Thousands of protesters showed up on the streets; they were shouting and carrying large posters.
Combining lengthy phrases 在复合句中使用逗号或用逗号来分隔短句会造成读者的困惑，这种情况应使用分号。
错误范例: Some useful subjects are English, which is an international language, math, which is used in all domains of sciences and social sciences, and philosophy, which underpins many other areas of study.
正确范例: Some useful subjects are English, which is an international language; math, which is used in all sciences and social sciences; and philosophy, which underpins many other areas of study.
冒号来条列下文，并告诉读者 “Here’s what I mean.”。通常在英文写作中，冒号不常被使用，除非您有许多内容需要列举，冒号的使用准则较为严谨，但也相对容易被记住。
Humans use five major senses: sight, hearing, smell, taste, and touch.
Martha realized that her worst fear was coming true: her son was being sent to war.
(*冒号后用独立的从句解释 Martha’s fear)
To the Central Valley Committee Chairman:
冒号后的第一个字母不要大写，除非是专有名词， is part of a quote, or is the first in a series of sentences:
错误范例: I have three desires: To eat, sleep, and work.
正确范例 : I have three desires: to eat, sleep, and work.
In Chapter 3, the author explains his theory: “Dogs have dreams, but they don’t dream as humans do. Their dreams reflect a primal desire for pleasure, whereas humans are preoccupied with the ego and self-image. This is equally true in wakefulness and sleep.”
There is one mantra that can sum up our position towards climate change: urgent action.
错误范例: Sarah and her friends loved spending time on the mountain : nature always held a special meaning for them.
正确范例: Sarah and her friends loved spending time on the mountain ; nature always held a special meaning for them.
The universe has always called to human beings; there could be no more final frontier than space.
Sam thought David was inviting him to the picnic to enjoy a nice day out; as it turned out, David was planning a surprise birthday party.
Our family members came all the way from Denver, Colorado; Rochester, Minnesota; and even Paris, France.
My main research objective is to isolate the cause of the disease, as well as to contribute to the existing literature; for this will bring an end to starvation across the continent, create new study designs related to epidemiology, and change the very paradigm of my research field.
错误范例: The specimens were treated properly, however, they were not stored properly.
正确范例: The specimens were treated properly; however, they were not stored properly.
*副词“however”表示的是连接两个独立的从句； 不要用逗号去连接两个不包含并列连词(and, but, or, nor 等等)的独立从句。
错误范例: The sun is wonderful: it produces light, which plants need to survive, it gives us warmth, which is useful for most life, and it makes a sad day happier, which is obviously a positive trait!
正确范例: The sun is wonderful: it produces light, which plants need to survive; it gives us warmth, which is useful for most life; and it makes a sad day happier, which is obviously a positive trait!