问题
选择题
The number of the trees in the world _____ getting smaller and smaller. [ ]
A. is
B. are
C. was
D. were
答案
答案：A
搜题请搜索小程序“爱下问搜题”
The number of the trees in the world _____ getting smaller and smaller. [ ]
A. is
B. are
C. was
D. were
答案：A
请根据以下资料回答：
某企业有甲、乙两个投资项目，计划投资额均为1000万元，其收益率的概率分布如下表所示：
| 市场状况 | 概率 | 甲项目 | 乙项目 |
| 好 | 0.2 | 20% | 30% |
| 一般 | 0.6 | 10% | 10% |
| 差 | 0.2 | 5% | -10% |
乙项目收益率的标准离差为______。
A．11.56%
B．10.25%
C．11.98%
D．12.65%