The scientists cleaned the phones using asolution made mostly__of____(61)alcohol. The aim of washing was to remove alldetectable traces of DNA. Theowners got their phones back for another week.Then the researchers___returned________ (62) the phones and cleaned each phoneonce more.

The scientists discovered DNA that _____belonged______(63) to the phone'sspeaker on each of the phones. Better samples werecollected from the outside ofeach phone, but those swabs also picked up DNAthat belonged to other people whohad apparently also ____handed______ (64) thephone

Surprisingly, DNA showed up even in swabsthat were taken immediately afterthe phones were scrubbed. That suggests thatwashing won't remove all traces of___evidence________ (65) from a criminal'sdevice. So cell phones can now beadded to the list of clues that can clinch (确定)a crime-scene investigation.

51.

A. name

B.pictures

C. shapes

D. traces

答案：d

52.

A. that

B. while

C.as

D.what

答案：a

53.

A. common

B. good

C. helpful

D. unique

答案：d

54.

A. behind

B. away

C. aside

D.over

答案：a

55.

A. visitors

B. travelers

C.scientists

D.criminals

答案：d

56.

A. until

B. before

C.unless

D. than

答案：d

57.

A. paper

B. document

C. device

D.file

答案：c

58.

A. checked

B. involved

C. tested

D. gathered

答案：b

59.

A. invisible

B.emotional

C. poisonous

D. magical

答案：a

60.

A. holds

B. watches

C. drops

D. covers

答案：a

61.

A. with

B.by

C. for

D. of

答案：d

62.

A. collected

B. answered

C. returned

D. used

答案：a

63.

A. moved

B.changed

C. belonged

D.turned

答案：c

64.

A bought

B. repaired

C.seen

D. handed

答案：d

65.

A. smell

B. evidence

C.sound

D.color

答案：b