第1题: [单项选择]In order to test if Stock A is more volatile than Stock B, prices of both stocks are observed to construct the sample variance of the two stocks. The appropriate test statistics to carry out the test is the:() A. ① B. ② C. ③ 参考答案:A 答案解析:
The F test is used to test the differences of variance between two samples.
第7题: [单项选择]My train arrives in New York at eight o’clock. The plane I would like to take from there ______ by then. A. would leave B. will have left C. has left D. had left 参考答案:B 答案解析:[解析] 根据上下文,by then中的then指的是eight o’clock tonight,因此该句应该用将来完成时。