根据句意圈出正确的单词或词组。
1. All of________ (they, them) are going to the park.
2. The birds are________ (singing, sing) in the tree.
3. ________ (How many, How much) children are there?
4. Three dogs have________ (twelve, twenty) legs.
5. There________ (are, were) not many cars before.