变成否定句,一般疑问句,并作肯定和否定句.（1）there is a bike under the tree.

（1）there is a bike under the tree.
否定句：There isn't a bike under the tree.
一般疑问句：Is there a bike under the tree
肯定,否定回答：Yes,there is./ No,there isn't.
（2）there are some apple trees in front of the house.
否定句：There aren't any apple trees in front of the house
一般疑问句：Are there any apple trees in front of the house
肯定,否定回答：Yes,there are./ No,there aren't.
（3）there was a football match yesterday afternoon.
否定句：there wasn't a football match yesterday afternoon
一般疑问句：Was there a football match yesterday afternoon
肯定,否定回答：Yes,there was./ No,there wasn't.
（4）there were some people in the street
否定句：there weren't some people in the street
一般疑问句:were there some people in the street
肯定,否定回答：Yes,there were./ No,there weren't.