• be + verb + -ing makes continuous forms: You're lying. They were reading. I've been swimming. We'll be having dinner at eight o'clock. You must be joking!
• be + past participle makes the passive: These books are printed in China. Where were you born? My phone's been stolen. The city had been destroyed. This work should be done soon.

• Do/does/did are used in the Present Simple and Past Simple: She doesn't understand. When did they arrive?
• Do/does/did are also used to express emphasis when there is no other auxiliary: I'm not interested in sport, but I do like tennis.

Have is used with the past participle to make perfect verb forms.

• Have and have got are both used to express possession in the present.
• Have to can be replaced with have got to to present obligation.
• Only forms of have (not have got) are used in all other tenses.
• Have (not have got) is used in many expressions: have breakfast, have a bath, have a party, have a good time.
• Have got is generally more informal. More common in spoken English, but in writing they are often interchangeable.

• In question tags: It's cold today, isn't it? You don't know Amelia, do you? You haven't been to Peru, have you?
• In short answers: 'Are you hungry?' 'No, I'm not.' 'Do you like jazz?' 'Yes, I do.'
• In reply questions (not real questions — show that the listener is paying attention): 'The restaurant was awful.' 'Was it? What a pity.' 'I love hamburgers.' 'Do you? I hate them.'

Modal auxiliary verbs are dealt with in Units 7 and 10.

Full verbs are all the other verbs in the language. The verbs be, do, and have can also be used as full verbs with their own meanings.

English tenses have two elements of meaning: time and aspect.

The time referred to is usually obvious from the context.

• Sometimes a present tense form can refer to the future: I'm meeting Jo later. (PC for near future)   The train leaves at 10.00 tomorrow. (PS for timetable)
• Sometimes a past tense form can refer to the present: I wish I could help you, but I can't.

• The simple aspect describes an action or fact that is seen to be permanent, often an action or event that happens repeatedly and consistently: The sun rises in the east.
• Remember state verbs rarely use the continuous aspect: verbs of the mind (know, understand, believe, think, mean), emotions (love, hate, like, prefer, care), possession (have, own, belong), and certain others (cost, need, contain, depend).
• The simple aspect expresses a completed action: She's written three letters this morning. I drink ten cups of tea a day.

• The continuous aspect expresses the ongoing nature of an activity. We are aware of the passing of time and the activity is not permanent: I'm staying with friends until I find a flat.
• Because the activity is seen in progress, it can be interrupted: We were walking across a field when we were attacked by a bull.
• The activity may not be complete: I was writing a report on the flight home. (I didn't finish it.)
• Some verbs always last a long time (live, work) and the continuous gives them limited duration and makes them temporary: I'm working as a waiter until I go to university.
• Some verbs last a short time (lose, break, cut, hit, crash) and are often found in the simple: I lost all my money. She's cut her finger.
• In the continuous, the action seems longer or habitual: I've been cutting the grass. (for hours)

• The action is completed before another time: Have you ever been to America? (some time before now) When I arrived, Peter had left.
• The exact time of the verb action is not important. The perfect aspect refers to indefinite time: Have you seen my wallet anywhere? I've lost it.
• Exception: Past Perfect, which can refer to definite time: I recognized him immediately. I had met him in 1992 at university.

• Passive sentences move the focus of attention from the subject of an active sentence to the object.
• In most cases, by and the agent are omitted in passive sentences because the agent is unimportant, isn't known, or is understood.
• In informal language, we often use you or they to refer to people in general to avoid using the passive.
• Many past participles are used like adjectives: I'm very impressed by your work. You must be disappointed with your exam results.