大革命失败后，***经过艰苦探索，逐步走出一条农村包围城市、武装夺取政权的革命新道路。探索这一道路的起点是（    ）

如图所示为一真空示波管的示意图，电子从灯丝K发出（初速度可忽略不计），经灯丝与A板间的电压U₁加速，从A板中心孔沿中心线KO射出，然后进入两块平行金属板M、N形成的偏转电场中（偏转电场可视为匀强电场），电子进入M、N间电场时的速度与电场方向垂直，电子经过偏转电场后打在荧光屏上的P点．已知M、N两板间的电压为U₂，两板间的距离为d，板长为L，板的右端到荧光屏的距离为b，不计电子受到的重力及它们之间的相互作用力．

Subject: Can you help?            

From: Rose

Dear Knowledgeable,

    I have a good friend, Ann. She is very clever and can speak English really well. A very important English speech contest for our whole city will be held next month. Our classmates all think Ann is the best person to represent the class in the school contest and make sure she will win. But the problem is that she's very shy and that she's terrified of speaking in front of other people.

    She can't tell others about it, because she doesn't want to let her friends down. I can't think of any good advice to give her, but you always come up with good solutions to people's problems. Can you give us some good advice？Do you think we can tell the truth to the rest of the students?

Yours,

Rose

东汉末年群雄并起，下列示意图符合公元222年三国鼎立的格局的是（    ）