能说明基因通过控制蛋白质的结构直接控制性状的实例是[ ]
A.白化病
B.苯丙酮尿症
C.皱粒豌豆
D.囊性纤维病
答案:D
Most volunteers are from universities, _________ it is not uncommon to see middle and primary school students too.
A.though
B.however
C.since
D.even if
当()卸下有困难时,可通过旁路管吹扫。
A、调节阀
B、流量计入口过滤器的盖
C、热水混合文氏管入口
D、泵