Verb tenses: adding -ed and -ing

The basic form of a verb is called the infinitive. It normally occurs with the word to as in ‘I want to ask you a question.’ Verbs may change their spelling according to which tense is being used.

The past tense refers to things that happened in the past. To make the past tense of regular verbs, the ending -edis added to the infinitive ('I asked her a question'). The present participle refers to things that are still happening. To make the present participle, the ending -ing is added to the infinitive ('I am asking her a question').

Often there's no need to make any other spelling changes when you add -ed and -ing to the infinitive but there are some cases when it's necessary to do so. Here are some rules to help you get it right:

Verbs ending with a silent e

If the verb ends with an e that isn’t pronounced (as in bake or smile), then you need to drop this final -e before adding -ed and -ing:

A very few verbs keep the final -e when adding -ing to distinguish them from similar words. For example, singebecomes singeing rather than singing (which is the present participle of sing).

Verbs ending with a vowel plus -l

If the verb ends with a vowel plus -l (as in travel or equal), then you need to double the l before adding -ed and -ingin British English:

This rule doesn’t apply in American English: see more information about the differences between British and American spelling

Verbs ending with a single vowel plus a consonant

If the verb ends with a single vowel plus a consonant, and the stress is at the end of the word (e.g. refer), then you need to double the final consonant before adding -ed and –ing:

If the verb ends with a vowel plus a consonant and the stress is not at the end of the word, you don’t need to double the final consonant when adding -ed and -ing:

If the verb has only one syllable and ends with a single vowel plus a consonant (e.g. stop), then you need to double the final consonant before adding -ed and -ing:

Verbs ending with two vowels plus a consonant

If the verb ends with two vowels plus a consonant, you should generally not double the final consonant:

bio-

a combining form meaning “life” occurring in loanwords from Greek ( biography  ); on this model, used in theformation of compound words ( bioluminescence  ).

Also, especially before a vowel, bi-.

Origin: 
 combining form of Greek bíos  life; akin to Latin vīvus  living, Sanskrit jīvas.  See quick

reference

Pronunciation: /ˈrɛf(ə)r(ə)ns/

noun

[mass noun]

• 1the action of mentioning or alluding to something:he made reference to the enormous power of the mass media[count noun]:references to Darwinism and evolution
  •  [count noun] a mention or citation of a source of information in a book or article:each chapter should have references to books covering the subject in greater depth
  •  [count noun] a source of information cited in a book or article.
• 2the use of a source of information in order to ascertain something:popular works of reference[as modifier]:a reference work
  •  the sending of a matter to an authority for decision or consideration:the publishers reprinted and sold the work without reference to the author
• 3 [count noun] a letter from a previous employer testifying to someone’s ability or reliability, used when applying for a new job:I was dismissed from the library, but with a good reference

verb

[with object]

• 1provide (a book or article) with citations of sources of information:each chapter is referenced, citing literature up to 1990
• 2mention or refer to:the media referenced our association in almost 40 articles

Phrases

for future reference

for use at a later date:she lodged this idea in the back of her mind for future reference

terms of reference

the scope and limitations of an activity or area of knowledge:the minister will present a plan outlining the inquiry’s terms of reference

with (or in) reference to

in relation to; as regards:war can only be explained with reference to complex social factors

hybrid

Pronunciation: /ˈhʌɪbrɪd/

noun

• 1 Biology the offspring of two plants or animals of different species or varieties, such as a mule:the bird was a hybrid of a goose and a swan
• 2a thing made by combining two different elements:jungle is a hybrid of reggae and house music
  •  a word formed from elements taken from different languages, for example television (tele- from Greek, visionfrom Latin).
  •  (also hybrid car) a car with a petrol engine and an electric motor, each of which can propel it.
• of mixed character; composed of different elements:hybrid diesel-electric buses
  •  bred as a hybrid from different species or varieties:a hybrid varietyhybrid offspring

adjective

Derivatives

hybridism

noun

hybridity

Pronunciation: /-ˈbrɪdɪti/

noun

Origin:

early 17th century (as a noun): from Latin hybrida 'offspring of a tame sow and wild boar, child of a freeman and slave, etc.'