在排焦区域作业,CO浓度不超过()mg/l可连续工作。
A.24
B.30
C.50
D.100
参考答案:B
—Have you brought with you? We won’t have time to come back.
—Don’t worry. All the things we need are here, in this big bag.
A.something
B.anything
C.nothing
D.everything
提出经典的条件反射学说的学者为()
A.华生
B.贝克
C.巴甫洛夫
D.斯金纳
E.沃尔普