1. Fresh-keeping bags generally cannot be heated directly in a microwave oven.

2. Since fresh-keeping bags are made of plastic material, heating them directly in a microwave oven may release some toxic substances, thereby contaminating food and endangering human health.

3. When food enters the microwave oven, you must be careful not to seal it too tightly. Secondly, you must put an appropriate amount of water to prevent the food from losing its original flavor after the water evaporates under high temperature.