阅读理解。
Everybody has a home. People have homes.Animals have homes. People have many different
kinds of homes. Animals have different kinds of' homes, too.
Some animals live in holes under the ground. The woodchuck ( 土拨鼠) lives under the ground. His
home has two doors. If any enemy comesinto one door, the woodchuck goes out through the other. Some animals live in holes in trees. Some squirrels（松鼠）build their nests（窝）high in trees. Most of the
birds live in nests. Crows(乌鸦)build their nests high in the mountains.
1. People have______.
A.different kinds of mountains
B. holes
C. different kinds of homes
D. all kinds of trees
2. The passage is about______.
A. some trees
B. the homes of some animals
C. animals' life
D. different animals
3. ______live under the ground.
A. All the animals
B. The woodchuck and the squirrel
C. Some animals
D. somebirds
4. How many doors does the woodchuck have in his house?
A. One.B. Two.
C. Three.D. No one.
5. Animals' homes are______.
A. not the sameB. in trees
C. in holesD. the same
表示电子对的转移，
表示单电子的转移，并写出各步可能的中间体。