请把下面句子括号里的词改成过去时态。 1. We ( fight)___ against virus, doubts, and uncertainty. 2. The doctors and nurses (work)___ day and night at the sacrifice of themselves. 3. Some (lose)___ their jobs. 4. Some (can't)___ pay their rent and bills. 5. Some people (don't)___ have chance to say goodbye to their families. 6. We (try)___ best to fight against fear, uncertainty and doubts.