玉米根尖成熟区的根毛大约有[ ]
A.420条
B.240条
C.360条
D.600条
答案:A
流脑的主要传播途径是()。
A.吸血节肢动物传播
B.水、食物、苍蝇传播
C.飞沫传播
D.土壤传播
E.血液、体液、血液制品传播
-I want to see Mr.Smith. We have an appointment.-I'm sorry, but he is not______at the moment, for the meeting hasn't ended.
A.available
B.accessible
C.approachable
D.advisable