A:白化病;在周围熟悉的4~10个家系调查
B:苯丙酮尿症;在患者家系中调查
C:红绿色盲;在学校内随机抽样调查
D:原发性高血压;在患者家系中调查
我国北方和南方地区的分界线大致为 ( )
读北半球部分地区海平面等压线分布图,回答下列问题.
Today is my birthday. I am a girl. My name is Han Mei. I'm nine years old. I have a birthday party. I have a birthday cake and many gifts. My father and my mother say“Happy birthday!”to me. I'm very happy.
根尖中生长最快的部位是( )