HBV感染者血清中一般情况下哪种颗粒最少（）
A.核状颗粒
B.丝状颗粒
C.棒状颗粒
D.小球形颗粒
E.Dane颗粒
参考答案：E
下列各组物质互为同分异构体的是
B．CH3—CH—CH3 和CH3—CH2—CH2—CH3
|
CH3
C． CH3—CH="CH—CH3" 和 CH=CH—CH2—CH3
D． CH≡CH 和CH≡C—CH3
Which of the following types of unemployment is most likely caused by long-run changes that eliminate some jobs while generating others for which unemployed workers are not qualified（）
A. Frictional.
B. Structural.
C. Cyclical.
