似蚓蛔线虫的感染阶段为
A．蛔虫受精卵、未受精卵
B．未受精蛔虫卵
C．蛔虫受精卵
D．感染期蛔虫卵
E．丝状蚴
参考答案：D
-He must be from Northeast China, which I can tell from his_____ .
-It may not be true, because some people can speak several_____. [ ]
A. accent; accent
B. accent; dialects
C. dialect; accent
D. dialect; dialects
下面属于电光源的主要技术指标有（）。
A.发光效率
B.色温
C.寿命
D.显色性
