心血管的基本中枢位于( )。
A．脊髓 B．脑桥 C．中脑 D．延髓 E．小脑
参考答案：D
There is a 30% chance that the economy will be good and a 70% chance that it will be bad. If the economy is good, your returns will be 20% and if the economy is bad, your returns will be 10%. What is your expected return（）
A. 15%.
B. 17%.
C. 13%.
集装箱重量、容积和面积的利用情况，可以用集装箱自重系数、集装箱比容和( )等指标衡量。
A．集装箱额定质量B．集装箱比面C．集装箱载运系数D．集装箱周转率
