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 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 -ed is 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 is no need to make any other spelling changes when you add -ed and -ingto the infinitive but there are some cases when it's necessary to do so and these are given below.
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:
Verbs ending in -ee, -ye, and -oe (such as free, dye, and tiptoe) do not drop the final -e when adding -ing:
A very few verbs keep the final -e when adding -ing to distinguish them from similar words. For example, singe becomes singeing rather than singing (which is the present participle of sing).
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 should not double the final consonant when adding -ed and -ing:
Note that in British English, when the consonant is an l, this rule is modified so that the l is always doubled, no matter which syllable of the base verb has the stress. So in British writing, you will see the spellings travelled, travelling; equalled, equalling, etc.
If the verb has only one syllable and ends with a single vowel plus a consonant (e.g., stop), then the final consonant should be doubled before -ed and -ing are added:
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:
Verbs ending in -c
If the verb ends in -c (e.g., panic), you need to add a -k before adding –ed and -ing, and also -er: