下面列出的都是残缺句子,请把它们改成完整的句子。 1. After returning from the beach. The children were exhausted. 2. John neglecting his duties and spending time on independent research. 3. Karen dropped calculus. Which she had dropped several times before. 4. Working together to save our environment. We can leave the world a better place than we found it. 5. Ellen returned the lost wallet to the man. Proving that she is an honest person. 6. Some errors in writing are serious. For example, sentence fragments, and run-on sentences.