Look at the words in blue in the text. Then choose the words to complete the rules. 1 We use if / when before something that is certain to happen. 2 We use if / when before something that is certain to happen. 3 After if and when we use the present simple will.

The Thames is not a long river. It is three hundred and thirty kilometres long and it runs into the sea. The English people call it “the Father of London”. London began on the Thames. When we go in a ship up the Thames we pass under London Bridge, the Tower Bridge and others. There is a museum of old ships on the Thames. These ships are from the history of Great Britain. One of these ships, the “Discovery”, went to the South Pole in 1901 — 1904.
If we go down the Thames we pass the port of London and get to Greenwich — a very old town. We can see the place where the Greenwich Meridian passes.

                                My Favourite Celebration
Celebration is a funny leisure.
  People like celebration,because they can have a rest and have a good time in the circle of family or friends.I also have my favourite celebration.It is my birthday.I think-It is one of the main holidays of my life.It's time when you become a year older,so clever,wiser ,more experienced.In this day I arrange a little party  ,where I invite my best friends.I enjoy when they celebrate me,wish health,happiness and luck and present me with gifts.After that we gather at one table and eat many taste dishes,especially birthday cake.Then we dance.
Every birthday leave in my memory only good moments!