脂肪还可以起到（）的作用。
A、保护心脏
B、保护器官
C、减少摩擦
D、保持体温
参考答案：B, C, D
有关静脉输液中微粒的主要来源，错误的是（）
A.输液器具
B.药物
C.配液和输液操作
D.环境污染
E.患者血液
Which of the following statements concerning arbitrage-free bond prices is FALSE（）
A. The riskier the bond, the greater is its credit spread.
B. It is not possible to strip coupons from U. S. Treasuries and resell them.
C. The determination of spot rates is usually done using risk-free securities.
