下列检测器中,属于浓度型检测器的是()。
A.FID
B.TCD
C.NPD
D.FPD
参考答案:B
低压蒸汽采暖系统管道中热媒的最大允许流速应符合的规定是( )。
A.汽水同向流动时30m/s;汽水逆向流动时20m/s
B.汽水同向流动时20m/s;汽水逆向流动时30m/s
C.汽水同向流动时25m/s;汽水逆向流动时20m/s
D.汽水同向流动时20m/s;汽水逆向流动时25m/s
Students in our school are encouraged to________more activities after class in order to broaden their
knowledge.[ ]
A.attend
B.join
C.take part
D.participate in