用量筒盛某种液体，测的液体体积V和液体与量筒共同质量m的关系如图所示，则量筒的质量为 g，液体的密度为 g/cm3．
40；1
—Hi, Mary. __________?
—Not so well. I can’t keep up with the other students.
A．How long have you studied chemistry
B．Who is teaching you chemistry
C．How is your chemistry study going
D．Where are you learning chemistry
腰椎间盘突出症与椎管内肿瘤最有鉴别意义的辅助检查方法是（）
A.X线片
B.MRI
C.CT
D.肌电图
E.超声波
