个人住房抵押经营类贷款资金回收周期一般较短，贷款年限通常最长为（）年。
A.5
B.8
C.10
D.12
参考答案：A
某饱和一元醛发生银镜反应时，生成了21.6 g 银，将等质量的该醛完全燃烧可生成26.4 g CO2，则该醛为（ ）。
A．丙醛
B．丁醛
C．己醛
D．乙醛
—It's 10 o'clock now. I must go.
—It's raining heavily outside. Don't leave ______ it stops. [ ]
A. since
B. until
C. when
D. because
