情态动词 must/mustn't 表义务 — 英语词汇题
题目
根据句意和首字母提示补全单词（用 must 或 mustn't 的正确形式填空）。
1. When you keep a cat, you m___ clean its litter box every day.
2. You m___ play loud music next to a sleeping dog. It will feel scared.
3. Lily's parrot is hungry, so she m___ feed it right now.