1If you work hard, you will pass the exam.
2Anna will phone Tom if she has time tonight.
3We'll go to the beach tomorrow if it doesn't rain.
<span>1 I bought an unusual football on ebay. David Beckham kicked it in the2004 European Cup Final!
2.There was an old Learjet for sale! A famous film star paid a lot of money for it.
3. The film star who bought the Learjet collects aeroplanes.
4 eBay is a very clever idea.It's the biggest market in the world.
5. I don't go out to work.I work at home on my computer.
6 I do all my shopping on the internet.What a great way to shop! </span>
Неопределенный артикль "а" употребляется там, где где говорится о чем - то одном из многих предметов. Допустим, ( I'm a child. Я ребенок. Один из многих)
Также этот артикль ставится там, где мы совсем ничего не знаем о предмете. (It's a dog) Это собака. Какая она - мы не знаем.
P.S. They talked last week
P.P. They had talked last week.
P.P.P They had been talking till last week.
Pr.S. у тебя есть.
Pr.P. They have just talked.
Pr.P.P. They are talking now.
F.S. They will talk next week.
F.P. They will have talked in an hour.
F.P.P. They will have been talking that time.