Silt and heavy run-off from farms in North Carolina were caused by （）.

A．Colds are always very dangerous.
B．Colds are often unpleasant though not dangerous.
C．Actually nothing can help get rid of colds.
D．The best way to keep colds away is to be healthy.

A．ordinary people like the television programme
B．ordinary people are interested in pictures of paintings, jewellery, etc.
C．the policemen can not catch the thieves themselves
D．ordinary people may help the policemen get useful information about the criminals