皮皮学，免费搜题
登录
搜题
【单选题】
How can researchers in 'sleep laboratories' tell that the animals they are observing are asleep or not?A.
They see if the animals respond to light and sound.
B.
They do this by observing changes in the animals' brain signals, breathing, heartbeat, and muscle activity.
C.
They see if the animals' eyes are closed.
D.
They can tell this by seeing if the animals lie down or not.
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
皮皮学刷刷变学霸
举一反三
【单选题】Life should consist of more than just a struggle for ___________.
A.
survival
B.
suivivor
C.
surpression
D.
surpass
【简答题】发动机异响,根据噪声来源可分为 , , ,和 。
【单选题】Life should consist of more than just a struggle for ___________.
A.
survive
B.
survival