_________he had only practiced the part a few times; he did it successfully beyond expectation.

A．Unless

B．If

C．Because

D． Although

尿中发现哪种蛋白可用于区别肾小球和肾小管疾病（）

A.低分子量蛋白

B.高分子量蛋白

C.中性蛋白

D.游离氨基酸

E.核蛋白