A:H2
B:NaCl
C:NaOH
D:H2S
A: Hello, Kate. ____
B: That's beautiful. I like it.
A: ____
B: I need four.
B: They're funny.
A: You can also buy a T-shirt for your friend.
B: ____
A. Good idea.
B. What about these caps?
C. Come and look at this cap.
D. How many caps do you need?
E. Let's go.
Lee is new in Yangzhou. Maybe he needs a _____for sightseeing.
如图,下列条件:∠1=∠2;∠3=∠4;∠2+∠3=∠5;∠2+∠3+∠A=180°;∠4+∠1=∠5,能判定AB∥DC有( )
如图所示,抛物线m:y=ax2+b(a<0,b>0)与x轴于点A、B(点A在点B的左侧),与y轴交于点C.将抛物线m绕点B旋转180°,得到新的抛物线n,它的顶点为C1,与x轴的另一个交点为A1. (1)当a=-1 , b=1时,求抛物线n的解析式; (2)四边形AC1A1C是什么特殊四边形,请写出结果并说明理由; (3)若四边形AC1A1C为矩形,请求出a和b应满足的关系式.