浸泡器械时，中性戊二醛水溶液的浓度应为：（）
A.2％
B.10％
C.70％
D.0.5‰
E.1‰
参考答案：A
I failed in the spoken examination last term and only then _______ the importance of practicing speaking English.
A．I had realized
B．had I realized
C．I did realize
D．did I realize
α粒子射程是（）
A.50～90μm
B.100～150μm
C.150～200μm
D.100～150nm
E.50～90nm
