对埃博拉出血热病例密切接触者进行追踪和医学观察，医学观察期限为自最后一次暴露之日起（）天。
A.7天
B.14天
C.21天
D.1个月
参考答案：C
More consumers are waiting for the further drop of housing prices with money in their hands rather than ______ houses, according to a report.
A．to buy
B．buying
C．buy
D．bought
其他动物胚胎
