"It has so much capability, so much more capability than any other vehicle, that I think we can start to contemplate missions like a Mars sample return, which requires a tremendous amount of lift capability because you've got to send a lander to Mars that still has enough propellant to return to Earth."
VOA: special.2011.04.11
That's got the lowest possible standard deviation of expected return and that's 25% stocks and 75% bonds with this sample period.
这个组合预期回报的标准差最小,在这一点上,投资组合,由25%的股票和75%的债券构成。
That's got the lowest possible standard deviation of expected return and that's 25% stocks and 75% bonds with this sample period.
这个组合预期回报的标准差最小,在这一点上,投资组合,由25%的股票和75%的债券构成。
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