Is there any difference between your idea and _____? [ ]
A. he
B. his
C. she
D. her
答案:B
奶牛产后65d内未见明显的发情表现,直肠检查卵巢上有一小的黄体遗迹,但无卵泡发育,卵巢的质地和形状无明显变化。该牛可能患有的疾病是()
A.卵泡萎缩
B.卵巢萎缩
C.持久黄体
D.卵巢机能减退
E.卵巢发育不良
HBV感染的主要标志是_______。