什么是品类宽度？

Earthquakes are common, and thousands of them happen each day.  But most are too weak to feel. During a  earthquake, there is often a great noise first.  Then the earth  terribly and many houses   down.  Railway tracks break and trains go off lines. A great many factories are destroyed. Thousands of deaths are caused, and many more lose homes.  Besides the great damage and deaths caused by the earthquake  ,other accidents such as fires often    . More buildings are destroyed and more deaths caused. It is well-known of the  of an earthquake, and for centuries man has been making researches on earthquakes. More than 2,000 years ago, ,a Chinese scientist named Zhang Heng invented a machine which could    from which direction the seismic waves（地动波）had come, and this machine is still   by scientists today. Now we know much more about earthquakes and   they happen, but we still can't tell exactly when and where earthquake will happen,  and cannot stop it from happening.

小题1:	A．real B．weak C．big D．small

小题2:	A．moves B．shakes C．jumps D．breaks

小题3:	A．get B．put C．set D．fall

小题4:	A．lonely B．later C．themselves D．itself

小题5:	A．follow B．copy C．come D．enter

小题6:	A．information B．questions C．dangers D．troubles

小题7:	A．as a result B．in fact C．for example D．as well

小题8:	A．find out B．think up C．point at D．look for

小题9:	A．improved B．repaired C．protected D．used

小题10:

A．where B．why C．what D．when