My lesson "O"

He felt no obligation to invite her for dinner. Perhaps it was his duty to inform the police of what he had seen.

If you say that someone has an obligation to do something or a duty to do something, you mean that they should do it.

He was busy with his official duties.

Your duties are the things that you do as part of your job.

I remember the occasion vividly.

An occasion is a time when something happens.

I met him only on one occasion.

You often say that something happens on a particular occasion.

The wedding was a happy occasion.

An occasion is also an important event, ceremony, or celebration.

You may have the opportunity of meeting him one day. She put the phone down before I had a chance to reply.

Don't use occasion to talk about a situation in which it is possible for someone to do something. Use opportunity or chance.

... the home of a sociology professor... the sister of the Duke of Urbino.

Of is used to show possession and relationships between people or things.

He's a very good friend of mine. I talked to a colleague of yours recently.

You can use of in front of mine, his, hers, ours, yours or theirs.

My sister stayed with us last week. He had his hands in his pockets.

Don't use of in front of me, you, he, she, it, us, they. Say my sister.

I heard Ralph's voice behind me.

You don't use of in front of names or very short noun phrases. Instead you use 's. For example, say: the man's car.

He offered me a biscuit.

If you offer something to someone, you ask them if they want to have it or use it.

She gave Minnie the keys.

If you put something in someone's hand and they take it, don't say that you offer it to them. Say that you give it to them.

He offered to take her home in a taxi.

If you offer to do something, you say that you are willing to do it.

He invited me to come to the next meeting.

If someone asks you to do something enjoyable, don't say that they offer you to do it. Say that they invite you to do it.

Mary is twenty-nine years old. The bones were 6,000 years old.

Old is used to state the age of a person or thing. For example, you say that someone is forty years old.

Sue lives with her five-year-old son.

You can also describe someone as, for example, a forty-year-old man.

How old are you? How old is the Taj Mahal?

You use old to ask about the age of a person or thing.

He looked really old. Her wardrobes were full of old clothes.

You can also use old to describe people or things that have lived or existed for a very long time.

I look after my elderly mother.

Elderly is a more polite word to describe old people.

We visited some old friends.

An old friend is someone who has been your friend for a long time. He or she is not necessarily an old person.

There were several photographs on his desk.

If something is on a surface, it is touching or supported by it.

He fell on on the floor. I put a hand on his shoulder.

You can use on to say where someone or something falls or is put.

He threw the envelope onto his desk.

Onto is used in a similar way.

George got on the bus with us. I met him on the train to Vienna.

You use on with names of vehicles such as a bus, train or aeroplane.

We are going see the play on Friday. Caro was born on April 10th.

You say that something happens on a particular day or date.

I once spent a night in that hotel. I have never forgotten her, though I saw her only once.

You use once to say that something happened one time in the past.

They were once very good friends, but now they never see each other. She had been a teacher once.

You also use once to say that something was true in the past, although it is no longer true. In this meaning, once usually goes after be or an auxiliary verb, or at the end of a sentence.

She stopped playing at once.

If you do something at once, you do it immediately.

She's not a model, but she looks like one.

You can use one instead of a singular noun when you have already mentioned the noun. For example, you say if you want a drink, I'll get you one.

I got this trumpet for thirty pounds. It's quite a good one. He earns money by buying old houses and building new ones.

You can use one or ones instead of a noun that follows an adjective.

We need a smaller fridge. This one's too big. She had a plate of soup, then went back for another one.

You can also use one after words such as this, each, that, my or another.

Grace was the only survivor. I was the only one smoking. He scored his only goal in that game.

You use only in front of a noun or one to say that something is true about one person, thing, or group and not true about anyone or anything else. In front of only put the or a word such as my, his or their.

The only English city he enjoyed working in was Manchester.

If you use another adjective or a number before the noun, you put only in front of it.

He opened the window and looked out.

If you open something such as a door, you move it so that it no longer covers a hole or gap.

I went to the door and opened it.

When you say that a person opens something, you must say what they open.

The door was open. He was sitting by the open window of the office.

When a door or window is not covering the hole or gap it is there to cover, you say that it is open.

A tall man opened the front door.

Opened is the past tense form or past participle of the verb open. You only use it when you are describing the action of opening something.

The hotel is opposite a railway station. The bathroom was opposite my room.

If one building or room is opposite another, they are separated from each other by a street or corridor.

Lynn was sitting opposite him.

If two people are opposite each other, they are facing each other, forexample when they are sitting at the same table.

Stinson has tented a home across from his parents.

Speakers of American English usually say across from rather than opposite in the above senses.

The opposite of right is wrong. He was the exact opposite of Herbert.

If two things or people are completely different from each other, you can say that one is the opposite of the other.

There is a mirror over the fireplace.

If one thing is over another thing, it is directly above it.

James stepped over the dog.

If you go over something, you cross it and get to the other side.

She was well over fifty.

If someone is over a particular age, they are older than that age.

He had flu over Christmas.

If something happens over a period of time, it happens during that time.

Roughly 4 million Americans travel overseas each year.

If you go overseas, you visit a foreign country that is separated from your own country by sea.

He met the president on a recent overseas visit.

Overseas is used in front of nouns. It has a similar meaning to foreign, but is more formal and is used especially when talking about business and politics.

If you say that someone is overseas, you do not mean that they are foreign.

You mean that they are visiting a foreign country.

I took no notice till I heard my own name mentioned. Now the industry's own experts support these claims.

You use own after a word like my, its or our to emphasize that something belongs to or is connected with a particular person or thing.

She says we cannot have our own key to the apartment. Each room had a style of its own.

You also use own to say that something belongs only to the person or thing mentioned.

She lived on her own.

If you are on your own, you are alone.

We can't solve this problem on our own.

If you do something on your own, you do it without any help from anyone else.