把下列各句改为被动语态
1. We clean our classroom every day.
Our classroom ________ ________ every day.
2. They produce silk in Suzhou.
Silk ________ ________ in Suzhou.
3. They speak English in class.
English ________ ________ ________ ________ in class.
4. He teaches us ten words every class.
Ten words ________ ________ to us ________ ________ every class.
5. We use keys for opening the door.
Keys ________ ________ ________ opening the door.