Ⅰ.牛刀小试：用适当的连词填空。
Jim spends a lot of money on books ________he is not rich.
Kate fell into sleep _______she was listening to the music.
—Is David at school today?
—No. He is at home _________he has a bad cold.
We won't have supper ______my mother comes back.
Speak to him slowly ___________he may understand you better.
_____she doesn't come on Sunday，I'll go fishing by myself.
It's four years ________I had left that small village.
_________the air moves，it is called wind.
We will go to the park ___it doesn't rain tomorrow.
—Do you have a bigger swimming pool?
—No，we don't. At least，not ______big ____yours.
That is _____an interesting book ______I can't stop reading it.
You'd better not leave the medicine _______the kids can get it.

Mark isn't coming to the concert ________________ he has got too much work to do.

—You bought the car about ten years ago?
—Yes.________ it's old，it still runs well.

We will have no water to drink ________ we don't protect the earth.

I enjoy fresh air so I always let the window open ________ it is really cold.