A(n)_______ of 10,000 dollars was _____ to anyone who could provide any clues leading to

the catch of the criminals who tried to murder the president.      [ ]

A. award; offered  

B. reward; given  

C. prize; provided  

D. reward; offered

利用万用表测量电阻值时，每换一次档，必须进行一次（）。