1)shall buywill be
will go
will phone
will cost
2)The children went to London. The Tour started at Hyde Park in themorning. The children fed the ducks and squirrels there. Then they took photos of Trafalgar Square. The next stop was the British Museum. They also visited the Tower of London. The children listened to the famous bell Big Ben. In the evening they were very tired. 
3) saw,caught,put,helped, found,were

think we will buy two return tickets.
Kate will be ten tomorrow.
My aunt will go to Canada next summer.
I will phone you in the evening.
I'm sure our 3-day tour will be more than 5000 roubles.
We will buy two return tickets.

The children went to London. The Tour started at Hyde Park in the morning. The children fed the ducks and squirrels there. Then they took photos of Trafalgar Square. The next stop was the British Museum. They also visited the Tower of London. The children listened to the famous bell Big Ben. In the evening they were very tired.

One day the children were on the ship. The sea was quiet. Suddenly they saw the pirates' ship. The pirates caught the children and put them in a dark room, but Kevin helped Steve and Maggie. In the room the children found the eighth magic pearl. Kevin put the eight pearls together and saved the Shell Kingdom. Kevin's parents were happy.