红外光谱是物质定性分析的重要手段之一,但不能用于物质的定量分析。 ( )
参考答案:错
皮划艇是奥运会的竞赛项目之一,已知比赛中皮划艇船桨的阻力臂是动力臂的3倍,则船桨是 杠杆(选填“省力”、“省距离”或“既不省力也不省距离”);若运动员在划船时对船桨施加的力是360N,则船桨受到水的作用力至少是 N.
Amy invests the following amounts at the end of Year l to Year4: Years 1 2 3 4 Amount1000 15002000 2500 ($) If it earns a 20% compounded interest rate, calculate the accumulated amount at the end of Year 4:
A.
B.
C.