收到报警信号后,报警控制器应具备立即以()信号向人们发出警报的功能。
A、电
B、声
C、热
D、光
参考答案:B, D
The majority of the students ____ to the teacher attentively. [ ]
A. are listening
B. is listening
C. are listened
D. is listened
人体内非酶系统的自由基清除剂有()
A.α-生育酚
B.β-胡萝卜素
C.胱氨酸
D.维生素C
E.超氧化物歧化酶(SOD.