已知抛物线C的顶点在原点，焦点为F（0，1），且过点A（2，t），

（I）求t的值；

（II）若点P、Q是抛物线C上两动点，且直线AP与AQ的斜率互为相反数，试问直线PQ的斜率是否为定值，若是，求出这个值；若不是，请说明理由．

根据句意及汉语提示填写单词。

1. I like the color of ____________ (紫色). What about you?

2. I got a ______________ (包裹) from my uncle yesterday.

3. Look! Some boys are ____________ (荡秋千) on the playground.

4. Lucy and other girls made a pretty castle with ______________ (沙子).

5. Jerry threw the ball _______________ (高地) into the air.