The writer's attitude towards science is______.

A．man has overthrown Newton' s laws of physics
B．man has solved a new set of gigantic puzzles
C．man has lost many scientific discoveries
D．man has given up some of the once accepted theories

A．the exposure of DNA to the public is unnecessary
B．the tiny cell in DNA is a neat little machine
C．man knows nothing about DNA
D．man has much to learn about DNA