下列是关于农作物秸杆利用观点，不正确的是（ ）

—______are Jim and Lily going hiking with their class?

—The day after tomorrow.

圆$x^2+y^2-4x+6y=0$的圆心坐标是（  ）

Tick, tick, tick! Good morning, Jim! It’s 6:30 now. It’s time 1 up. Do you know me? I’m your new friend. My name is Clock. Look 2 me. I have no feet, 3 I can walk with my hands. I have no mouth, but I 4 speak to you. Now please listen to 5. Today is Monday. You have many things to do. Classes 6 at 8:00. You have four classes in the morning and two classes in the afternoon. After 3:40 you have a basketball match 7 Class Two. You come 8 at 5:40. You have supper at 6:00. You 9 CCTV news at 7:00. And you go to bed at 9:30. Now please get up quickly and have your breakfast or（否则）you will be 10.

用与竖直方向成θ角（θ＜45°）的倾斜轻绳a和水平轻绳b共同固定一个小球，这时绳b的拉力为F₁．现保持小球在原位置不动，使绳b在原竖直平面内逆时转过θ角后固定，绳b的拉力变为F₂；再转过θ角固定，绳b的拉力为F₃，则（   ）