1. I don't think he can swim across the Changjiang River. (改为同义句)
    I don't think he is _____ _____ swim across the Changjiang River.
2. You should walk your dog once a week. (对划线部分提问)
    _____ _____ should you walk your dog?
3. We must clean our classroom every day? (对划线部分提问)
    _____ must we _____ every day?
4. Walk the dog at 7 a.m.. (改为否定句)
    _____ _____the dog at 7 a.m..
5. His dog is the cleverest of all. I don't think so. (合并为一句)
   I _____ think his dog _____ the cleverest of all.