阅读短文填空。 According to Center for Disease Control and Prevention (CDCP 疾病控制预防中心), if you don't often wash your hands, you can pick up viruses (病菌) from many places and make yourself ill. You're at risk every time you touch your eyes, nose or mouth, In fact, one of the most common ways people catch colds is by rubbing their noses or their eyes when there are cold viruses on their hands. If you don't often wash your hands, especially when you're sick, you may spread the viruses directly to others. You should wash your hands in the following situations: ● After using the bathroom. ● After blowing your nose or coughing ● Before eating , serving or preparing food. ● After visiting anyone who is ill ● When your hands are dirty. There's right way to wash your hands. Follow these simple steps  to keep your hands clean. ● Use warm water ( not cold or hot). ● Wash for 15 seconds. ● Rinse (冲洗) well under warm running water and dry them with a clean towel. 1. Correct way to wash your hands.                         Using running water which is _____. 2. Situations in which you must wash your hands.     After using the  _____. Before having _____. After visiting _____ people. 3. Time needed to wash your hands.                        Fifteen _____.