18.
Good evening, this is Mary Lamb again with the weather report. A strong wind from the north is coming to London in twenty-four hours. This wind will bring us the first snow of this year. With that snow, the temperature will drop to three or four below zero. So remember to keep warm and watch out for the poor road conditions. If you like skating, however, here is our good news for you. This low temperature will last for at least two weeks and London will be a world of white. And that ends our special report for today, April 1,2004. Next, a song for you, I Am Dreaming of a White Christmas.

19.
Should students make friends on line ?Some people say yes .The internet helps make many friends .Chatting on line ,students can more freely express their feelings and opinions ,and even get help with their foreign language studies .
Others ,however, think students should not .They say making friends on line is a waste of time ,which should be spent more meaningfully on study .Besides ,some students get cheated on line.
It is my opinion that students should place their study ,health and safety before other things .As for friendship ,we can readily find it in our classmates and other people around us.

20.
A healthy diet and regular exercise may help to prevent obesity (肥胖) among children. Take Li Ming for example.
Li Ming used to be a healthy boy, but over a year ago, into the habit of eating a lot of junk food and snacks. Besides, he spent a lot of time lying on the sofa, watching TV, and did little exercise. As a result, he put on so much weight that he found it difficult to climb the stairs.
So Li Ming decided to change the unhealthy life style. He began to have a balanced, healthy diet. He also took part in various sports activities such as swimming, skating, running and playing basketball. Months later, Li Ming became as fit as before.