第1个回答 2024-04-04
We are all familiar with the four types of hyphens in English written communication: en dash, em dash, en rule, and minus sign. However, many learners are unsure of their proper usage. Let's delve into the specific applications of each.
1. En dash: Used to indicate a range between two numbers
Example: The mean age of the patients was 55 years (46–69 years).
Temperature in the room was kept at 25–28°C.
Note that if "between...and" or "from...to" is used, the en dash is not necessary.
2. Em dash: A less common punctuation mark that signifies an upcoming detailed explanation
Generally, it can be replaced by a colon (when there is only one em dash) or a comma (when there is an em dash before and after the content).
Example: We have discovered a new function of FOXN1—recruiting melanocytes to deposit melanin into the epithelial cells. (Colon replacement possible)
The new function of FOXN1—recruiting melanocytes to deposit melanin into the epithelial cells—was discovered through our analysis of Foxn1-overexpressing mice. (Both commas possible)
The em dash creates a longer pause than a comma, suggesting that the following content is somewhat unexpected and warrants attention. Hence, excessive use of em dashes in an article is not recommended, as a few strategic uses can make the text more engaging.
3. En rule: This is the most commonly used hyphen and is typically employed in the following situations:
a) Connecting parts of compound words, such as X-ray, Editor-in-Chief, meta-analysis; or linking a word with a prefix, like anti-inflammatory, non-coding.
The usage of en rules is widespread, but there are no strict rules. Some words may have different formats preferred by different authors (e.g., Editor in Chief, noncoding), while others trend towards a single format (e.g., X-ray, meta-analysis, anti-inflammatory). Over time, the preferred format of some words may evolve, as seen with up-regulate and down-regulate, which are now commonly written as upregulate (upregulation) and downregulate (downregulation). It is crucial to maintain consistency within a document.
b) Joining two to three words to act as an adjective modifying the following noun. The en rule is essential in this case.
Example: Eight-week-old mice were given a high-fat diet for 12 weeks. (Note that "eight-weeks-old" is incorrect.)
LPS-induced apoptosis of HUVECs was ameliorated by pre-treating the cells with VEGF.
When cells reached confluency, various stimulants were added into the culture medium, followed by a 24-hour incubation.
If the same meaning is not used as an adjective before the noun, the en rule is not needed.
Example: At the time the experiment started, the mice were eight weeks old.
When cells reached confluency, various stimulants were added into the culture medium, and the cells were further cultured for 24 hours.
Words connected by an en rule are usually two to three in number and should not be used to connect an extended series of words.
4. Minus sign: Indicates subtraction or a negative number
In mathematical formulas, a space should precede and follow the minus sign.
Example: Tumor growth inhibition rate was calculated as (1 - tumor volume of treated group/tumor volume of control group) × 100%.
When indicating a negative number, there is no space between the minus sign and the following number.
Example: The samples were stored at -20°C until use.
Final concentration of MgCl2 in the buffer was 0.2 g L^-1.详情