โCostโ can be either a noun or a verb.
As a noun, โcostโ can refer to the money needed to buy or do something (e.g., โthe cost of housing is too highโ) or the loss something requires or results in (e.g., โthe war was won, but at the cost of many livesโ).
As a verb, โcostโ is usually a transitive and stative verb used to describe the price of something or the loss resulting from something (e.g., โher new suit cost $500,โ โher credit card debt cost her her marriageโ).
In professional environments, โcostโ can be used as an action verb meaning to calculate how much something will be (e.g., โwe need to cost the new projectโ). The simple past tense of โcostโ in this context is โcosted.โ
Read this FAQ: Is cost a verb?
Stative verbs (aka state verbs) describe a state, condition, or perception. The state can be physical, mental, or emotional (e.g., โbe,โ โbelieve,โ โloveโ).
Dynamic verbs (aka action verbs) describe an action carried out by or on the subject (e.g., โeat,โ โthrow,โ โrunโ). The action can be cognitive or sensory as well as physical (e.g., โhe is thinking about buying a house,โ โshe looked at the scheduleโ).
Some verbs can be either dynamic or stative depending on whether they are describing an action or a state.
Read this FAQ: What is the difference between stative and dynamic verbs?
We change regular verbs to the simple past and past participle forms by adding โ-edโ (or โ-dโ if the verb already ends in โeโ). For example, โtalkโ becomes โtalkedโ and โdanceโ becomes โdanced.โ
Some regular verbs change their spelling in other ways, such as doubling the final letter or replacing โ-yโ with โ-ied,โ but they still follow predictable patterns. Regular verbs are always the same in their past and past participle forms.
Irregular verbs donโt follow the regular rule of adding โ-edโ or โ-dโ to form the simple past and the past participle forms. They can change in a variety of ways or not change at all, and their simple past and past participle forms can be (but arenโt always) different.
For example, โgoโ becomes โwentโ in the simple past but is โgoneโ as a past participle, while โhitโ is the same in all three forms.
Read this FAQ: Whatโs the difference between regular and irregular verbs?
Irregular verbs donโt follow the regular rules for forming the simple past tense and the past participle form. While regular verbs need the addition of โ-edโ (or โ-dโ if the verb already ends in โeโ), irregular verbs can change in a variety of ways or not change at all.
Here are some examples of irregular verbs in the simple past and past participle forms:
| Base form |
Simple past |
Past participle |
| be (is, am, are) |
was/were |
been |
| do |
did |
done |
| eat |
ate |
eaten |
| go |
went |
gone |
| sing |
sang |
sung |
When you’re conjugating irregular verbs into different verb tenses, QuillBot’s free Grammar Checker can help you avoid errors.
Read this FAQ: What are some irregular past tense verbs?
The past continuous tense (aka the past progressive) is a past tense verb form used to describe actions that were ongoing in the past. It often describes actions that were happening at the same time or that were happening when something else occurred.
Here are some examples of the past continuous tense:
- I was surfing when my surfboard broke.
- She was smiling as I was telling the story.
- We were singing karaoke while our friends were dancing.
- Jemal was always studying on Friday nights.
Read this FAQ: What are some examples of the past continuous tense?
โWasโ and โwereโ are both simple past tense forms of the stative verb โbe.โ The correct form to use depends on the subject.
โWasโ is used for most singular subjects, including first person and third person (e.g., โI was,โ โshe wasโ).
โWereโ is used for plural subjects (e.g., โwe were,โ โthey wereโ), but itโs also used for the second person regardless of whether the subject is singular or plural (e.g., โyou wereโ).
Whether โwasโ or โwereโ is correct can also depend on whether youโre using the subjunctive mood or indicative mood. The subjunctive mood is used to express wishes, hypotheticals, and suggestions (e.g., โif I were you, I would say somethingโ).
QuillBot’s Grammar Checker can help you ensure you’re using was and were correctly.
Read this FAQ: What is the difference between was and were?
Although โcould ofโ is sometimes used in colloquial speech, the correct form is โcould haveโ or the contraction โcouldโve.โ
โCouldโ is a modal auxiliary verb and โhaveโ can either be an auxiliary verb or a main verb. Modals and auxiliaries are used with a main verb to change its tense, mood, or voice. When โcould haveโ modifies a main verb, it means that something may have been possible in the past but didnโt happen (e.g., โwe could have stopped for coffee if weโd left earlierโ).
Read this FAQ: Is it โcould ofโ or โcould haveโ?
โWas,โ like other forms of โbe,โ can either be a main verb or a helping verb (aka auxiliary verb). As a main verb, โbeโ is always a stative and linking verb (e.g., โI was a doctorโ). As a helping verb, it helps to form the passive voice (e.g., โthe house was soldโ) and progressive tenses, such as the present progressive (e.g., โI was selling my houseโ).
Read this FAQ: Is โwasโ a helping verb?
The most common linking verbs are โbe,โ โbecome,โ and โseem.โ These are also known as โtrue linking verbs.โ
Other common linking verbs include โappearโ when it means โseemโ and sensory verbs such as โtaste,โ โfeel,โ and โsmellโ (e.g., โthis coffee tastes bitter,โ โI feel goodโ).
Apart from โbe,โ โbecome,โ and โseem,โ all linking verbs can also be action verbs depending on whether theyโre describing the state of the subject or an action.
Read this FAQ: What are some common linking verbs?
โLookโ is a linking verb when it is describing a quality of the subject (e.g., โyou look happyโ or โthe food looks goodโ).
When it is describing the act of looking at something, โlookโ is an action verb (e.g., โhe looked at the TVโ).
Read this FAQ: Is โlookโ a linking verb?