给出下列五个命题:
①函数y=f(x),x∈R的图象与直线x=a可能有两个不同的交点;
②函数y=log2x2与函数y=2log2x是相等函数;
③对于指数函数y=2x与幂函数y=x2,总存在x0,当x>x0 时,有2x>x2成立;
④对于函数y=f(x),x∈[a,b],若有f(a)•f(b)<0,则f(x)在(a,b)内有零点.
⑤已知x1是方程x+lgx=5的根,x2是方程x+10x=5的根,则x1+x2=5.
其中正确的序号是____ .
从____面看到的图形是 。
选择恰当的句子补全下面的对话。
A: Hi, Jim. ____
B: I get up at 6:30. ____
A: Usually at 6:00. ____
B: I often wash my clothes and clean the windows.
A: Wow! ____
B: Do you do housework (家务活), too?
A: Yes, sometimes. ____
B: Sounds interesting!
A. You're so hard-working.
B. When do you get up on Saturdays?
C. What do you do on the weekend?
D. But I often play computer games.
E. What about you?
围棋的棋盘是由纵、横各19条线交叉组成的.下棋时,棋子都要放在纵线与横线的交叉点上.你能算出棋盘上一共有多少个交叉点吗?