A:属于生命系统层次中的最小层次
B:没有细胞结构,只能寄生在活细胞中
C:能在无机环境中繁殖. 因此具有传染性
D:可用煮熟冷却后的肉汤大量培养. 用于科学研究
读一读,选一选
____ Is your father here today? A. No, I don't.
____ What does your mother do? B. He's a businessman.
____ Do you want to be a head teacher? C. No. He's in Australia.
____ What does he do? D. She's a head teacher.
我们打开《中国行政区划图》、《世界地形图》、《中国交通图》,可以发现它们都具备____ 、____ 、____ 三个要素.