不属于观察调查法的优点是()
A、直观且可靠
B、可以排除语言交流或人际交往可能发生的误会和干扰
C、简便易行,灵活性强
D、对调查人员的业务水平要求较低
参考答案:D
Fill in the blanks. 根据提示将单词补充完整。
1. A: W (谁) is it? B: It's me.
2. L (看)! I see a big brown cow!
3. What is the girl doing n (现在)?
4. Kim doesn't s (睡觉). She is laughing.
5. A: What are you doing? B: I'm p (指).
6. The boy b (在……后面) me is reading books.
7. The girl likes to d (画画).
8. You are q (安静的).
9. A train is q (快的).
10. I am t (渴). I would like some tea.
关系运算中的选择运算是( )。
A) 从关系中找出满足给定条件的元组的操作 B) 从关系中选择若干属性组成新的关系的操作C) 从关系中选择满足给定条件的属性的操作 D) A)和B)都对