( )是指以各种货币作为基础工具的金融衍生工具。
A．股权类产品的衍生工具 B．货币衍生工具C．利率衍生工具 D．信用衍生工具
参考答案：B
The fact has worried many scientists______ the earth is becoming warmer and warmer these years.[ ]
A. what
B. which
C. that
D. though
什么叫矿井通风阻力？
