若x1,x2是方程x2=4的两根,则x1+x2的值是 [ ]
A、8
B、4
C、2
D、0
答案:D
补全对话(5小题,每小题2分,共10分)
A: Morning, Tom. You don’t look well. ________小题1:___________________?
B: Well, I have got a cold. But it’s not serious. Hey, Jack, did you see the movie on CCTV 6 last night?
A: No, I didn’t.________ 小题2:______________________?
B: Harry Potter Ⅲ. It was so exciting. So, what were you doing at that time?
A: ________小题3:________________. I’m not good at English, you know.
B: But English is not very hard to learn. __________小题4:______________.
A: Thank you for your advice. _________小题5:_______________________?
B: It’s nearly 7:50. Hurry up, or we’ll be late fir school.
遇有火灾、地震、台风、冰雪、洪水、泥石流、沙尘暴等灾害发生时,巡线有何要求?