在孟德尔的具有两对相对性状的遗传实验中,F2出现的重组性状类型中能够稳定遗传的个体约占总数的 [ ]
A.1/4
B.1/8
C.1/16
D.1/9
答案:B
______ difficult the problem was, he tried his best to solve it.[ ]
A. No matter
B. Although
C. Whatever
D. However
莱姆病的主要传染媒介是()
A.蜱
B.马蝇
C.蚊
D.鹿蝇
E.虱