There are some birds in the tree. →There aren't any birds in the tree.
Would you like some orange juice?
I have a knife and a ruler.
→I don't have a knife or a ruler.
3.a lot of (=lots of)变为many或much。如：
They have a lot of friends.（可数名词）
→They don't have many friends.
There is lots of orange in the bottle.（不可数名词）
→There isn't much orange in the bottle.
I have been there already.
→I haven't been there yet.