Heating water evaporates and becomes old. A lot of food heating have this phenomenon, such as: steamed bread, corn. You can put a bowl of water next to the heating at the same time at the same time. There is a steam function of the microwave oven can be used to steam. Or the fish bowl to get more soup over the fish, and then covered with a lid on top and then heated to prevent water loss. You can also buy a microwave special steam box, the following can be added to the kind of water, used to steam fish, in short, the food inside the lack of water on the dry.