Today’s topic is the use of hyphens with phrases made from participles (such as in my cleverly devised blog title—but not in this sentence, as you will see why).
Participles come in two flavours: present and past.
Present participles always end in -ing. You can change any verb and make it into a present participle. Here are some examples:
biking, flying, diving, skiing
Past participles are the third form of the verb. You probably remember memorizing these forms—the last one is the past participle.
In regular verbs, the past participle is the same as the simple past—as in these examples:
We often combine a participle with another word to make a compound phrase. The whole phrase can then describe a noun. Here are some examples:
(1) dish-washing detergent
(2) self-inflicted wounds
(3) horse-drawn carriage
(4) money-saving techniques
(5) clinically-proven results
Which of the above five examples are formed from present participles and which from past participles? (Answer: (1) and (4) are present; the others are past participles.)
When to hyphenate
Compound participle phrases are always hyphenated when they come before the noun they describe (as in the five examples above).
When they follow the noun they describe, hyphenation is optional—though never wrong.
The wounds were self inflicted. Or: The wounds were self-inflicted.
The results were clinically proven. Or: The results were clinically-proven.
If a participle is preceded by an adverb that ends in -ly, the compound is never hyphenated:
recently discovered fossils
badly managed accounts
In the following sentences, (1) find the participle phrase and the noun or noun phrase it describes; (2) hyphenate as needed; (3) indicate whether the participle is a present or past one.
Answers follow. Number (1) is done by way of example.
1) A variety of food preserving methods are used to prevent bacteria from spoiling food.
Answer: food-preserving methods (present)
2) All early airplanes were powered by gasoline driven piston engines that spun propellers.
3) Fiberglass reinforced plastic combines the flexibility of a plastic with the strength of the fiberglass that is embedded in the plastic.
4) The most commonly used type of primary cell is the zinc carbon battery or dry cell.
5) The shock absorbing properties of rubber make it useful for car suspensions.
6) Most of the world’s 25 fastest growing cities are in the developing world.
7) Today, the main uses of steam turbines are in power plants and for the propulsion of nuclear powered ships.
8) Microphones turn sound into an electric signal that can drive a groove cutting machine.
9) Modern radio telescopes scan the sky with huge, bowl shaped dishes that reflect radio signals onto small horn antennae.
10) Cheap, factory made wristwatches made time available to everyone by the beginning of the 1900s.
2) gasoline-driven piston engines (past)
3) Fiberglass-reinforced plastic (past)
4) most commonly used type of primary cell (past)
5) shock-absorbing properties (present)
6) fastest-growing cities (present)
7) nuclear-powered ships (past)
8) groove-cutting machine (present)
9) bowl-shaped dishes (past)
10) factory-made wristwatches (past)
Image at top courtesy of Free Digital Photos.
The ten sentences for the exercise were taken from: Taylor, Charles, ed. The Kingfisher Science Encyclopedia. Boston: Kingfisher, 2000.