利用人粪尿、禽畜粪尿和农作物秸秆生产沼气和高温堆肥所应用的原理（ ）
A．光合作用
B．呼吸作用
C．蒸腾作用
D．扩散作用
答案：B
肝在五行中属（）
A、金
B、水
C、木
D、火
On 1 January, Hellen’s portfolio is valued at $1000000. Hellen want to make a $100000 payment to buy a house on 31 December of the same year, but does not want the year-end portfolio value to fall below $1000000. The expected annual return on the investor’s existing portfolio is 15 percent with an expected standards deviation of 20 percent. The risk-free rate is 8%. The safety-first ratio for the portfolio is closest to:（）
A. 0.10.
B. 0.25.
C. 0.35.
