1. Apple is my _________ fruit. I like to eat it every day.
2. Cold fever is _________ in winter because of cold weather. More people get sick at this time.
3. Engineers and scientists should _________ a car using water as fuel to save the energy.
4. Radios were popular decades ago, but now they are _________. Few people use them.
5. Fried egg is a _________ menu. We can do it very easily.