The most important diamonds are 1 we never see-the diamonds used in industry． Th

    The most important diamondsare    1    we never see-the diamonds used in industry． Their value lies in theirhardness, not their beauty, and in the thousands of   2   they do．

    Industrial diamonds makethe needles for hifi phonographs (唱机)． Diamonds cut    3    solidrock in search of oil． Dentists use diamonds too often    4   a powder glued(粘合) to paper or a wheel．Other diamond wheels cut and    5    stones and cut metal parts for all kinds of engines．They are    6    usedto make wheels for grinding(磨光)and polishing(擦亮)metals．

  Most marvelous of all    7    thediamond dies． These are flat diamonds through which small    8    havebeen drilled(钻空)．Whenmetal is    9    through the small hole in the diamond, it comes out as thinwire．

    Cars, airplanes, nails, tincans, radios, refrigerators, and most electrical 10 could not be madewithout using industrial diamonds．

1．A．which

B．that

C．those

D．what

2．A．jobs

B．works

C．duties

D．functions

3．A．split

B．apart

C．break

D．through

4．A．with

B．by

C．as

D．like

5．A．polish

B．break

C．sharpen

D．flatten

6．A．yet

B．still

C．too

D．also

7．A．is

B．are

C．was

D．were

8．A．eyes

B．gaps

C．slits

D．holes

9．A．tugged

B．towed

C．pulled

D．hauled

10．A．equipment

B．device

C．apparatus

D．instrument

试题答案

答案：C;A;D;C;A;D;A;B;C;A