问题
选择题
— What's the temperature outside?
— It's thirty degrees. I'm going to __________ my sweater.[ ]
A. put on
B. take off
答案
答案：B
搜题请搜索小程序“爱下问搜题”
— What's the temperature outside?
— It's thirty degrees. I'm going to __________ my sweater.[ ]
A. put on
B. take off
答案：B
甲公司股票与乙公司股票收益率的概率分布如下所示：
| 行业正常年份 | 行业危机 | ||
| 股市牛市 | 股市熊市 | ||
| 概率 | 0.5 | 0.3 | 0.2 |
| 股票甲 | 25% | 10% | -25% |
| 股票乙 | 10% | -5% | 20% |
甲公司股票与乙公司股票的收益之间的协方差是多少