We must ______ that the experiments are carried out as rigidly as possible.

A．made their greatest contribution when they were living in Europe
B．need just a laptop to finish all their scientific experiment
C．often cooperate with each other to create a new theory
D．pay little attention to the research in the universe

A．He had made great achievements at a very young age.
B．He founded only three famous theories in his whole life.
C．He was very ordinary among those notable scientists at that time.
D．He made today's physical researches more quickly and comfortable.