do youto get to school?

 is it between Shanghai and Nanjing?

 is the capital of Britain?

    The students were 1their chemistry (化学) class. Miss Li was telling the children what water was2. After that, She asked her students, "What's water?"3one spoke for a few minutes. Miss Li asked again, "Why don't you answer my4? Didn't I tell you what water is like?" Just then a boy put up his hand and said, "Miss Li, you told us that water has no colour and no smell. But5to find such kind of water? The water6the river behind my house is always black and it has a bad smell." Most of the children agreed with him. "I'm sorry, children," said the teacher, "Our water is getting dirtier and dirtier. That's a problem."

    Most of us use alarm clocks to wake up at the right time for work. We look at our wto know when to catch a bus or train. However, there is also a right time to eat, sleep, exercise, and take medicine, too. We can't look at a clock for the right time for these activities. We must listen to the clock inside our b our biological clock.

    Today, doctors are learning more about chronobiology (生物钟学), the study of biological clocks. They are learning about the iof time for our bodies. For example, it is best for people to go to sleep at the stime every night and to eat only when they're hungry. Also, doctors have discovered that some i, such as heart attacks, occur most often in the morning. This information tells them that the btime to take heart medicine may be at night. When patients take heart medicine at night, they may prevent a heart ain the morning.