唾液淀粉酶作用最适宜的pH是
A．2.0～3.5 B．3.5～5.0 C．6.7～7.0 D．7.0 E．7.5～8.5
参考答案：D
The couple are unable to have children of their own, but hope to _______ one.[ ]
A. adapt
B. receive
C. adopt
D. keep
甲型H1N1流感病毒是引起“甲流”的病原体．下列各项中能表明该病毒属于生物的是（ ）
A．由有机物组成
B．具有细胞结构
C．能在动物体内繁殖
D．能使人体患病
