问题
选择题
—How do you go to work, Ted? — ________.[ ]
A. Fine, thanks
B. I'm good at it
C. By bus
D. Nice to meet you
答案
答案：C
搜题请搜索小程序“爱下问搜题”
—How do you go to work, Ted? — ________.[ ]
A. Fine, thanks
B. I'm good at it
C. By bus
D. Nice to meet you
答案：C
设有关系R，S和T如下。关系T是由只和S经过什么操作得到的
R
| A | B | C |
| 1 | 2 | 3 |
| 4 | 1 | 6 |
| 3 | 2 | 4 |
| A | B | C |
| 4 | 1 | 6 |
| 2 | 7 | 1 |
| A | B | C | D | E |
| 1 | 2 | 3 | 7 | 1 |
| 3 | 2 | 4 | 7 | 1 |
