脾切除无效的疾病是（）。
A.遗传性球形细胞增多症
B.阵发性睡眠性血红蛋白尿
C.海洋性贫血
D.ITP
E.脾功能亢进
参考答案：B
什么是分子克隆？主要有哪些步骤？
Since______beginning of photography,______inventors have tried to make______ photographs that duplicate______natural colors.
A．the.../.../.../ B．the...the.../...the C．/.../.../.../ D．/...the...the.../
