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举一反三
【单选题】Los Alamos National Laboratory scientists are using a new technique to see fingerprints on surfaces that typically make them invisible. The method uses a technology called mini-X-ray fluorescence (荧光)...
A.
The chemicals of adolescent prints disappear within a shorter time.
B.
It takes a longer time to detect the chemicals of adolescent prints.
C.
It is more difficult to determine the chemicals of adolescent prints.
D.
The adolescent prints contain fewer useful chemicals for research.