将浓度为0.1mol·L-1HF溶液加水不断稀释,下列各量始终保持增大的是 [ ]
A. c(H+)
B.
C.
D.
答案:D
1919年北京大学音乐研究会创办()。
After a vessel transmits the original distress message,what signal should be sent to allow ships to take RDF bearings?()
A.SOS three times
B.Additional transmissions to aid direction finding
C.E for one minute,followed by T for one minute
D.Two tones,10-15 seconds each