不定项选择题 
What is the discovery of the first experiment? ( )
A The left brain was relatively more active than the right brain on the first night, and the difference disappeared on the second night.
B
During the two nights of sleeping in the new environment the subjects did not respond differently.
C
Asymmetric sleep in a new environment was a protective mechanism in humans.
D
Brainwave activity in the left brain was more intensive during the two nights of sleep.
