Mr. Brown: Good morning. My name is Edward Brown. I'm your new ____, and I moved in yesterday.

Mrs. Smith: Good morning, Mr. Brown. May I help you?

Mr. Brown: I'm trying to do some work now. But I'm afraid your children are making too much ____.

Mrs. Smith: Oh, I'm sorry, Mr. Brown. But you know it's____ to keep little boys quiet.

Mr. Brown: But I can't stand it any more. I couldn't work and I couldn't ____ at all last night.

Mrs. Smith: I'm very, very sorry. I'll do my best to keep them quiet. But I'm not sure it'll work.

Mr. Brown: Well, it seems I have to put up with it now.

Mrs. Smith: Don't ____. My husband will come back from business tonight. And the boys always listen to him.

如图所示，两个质量相同的物体A和B紧靠在一起，放在光滑的水平桌面上，如果它们分别受到水平推力F₁和F₂作用，而且F₁＞F₂，则A施于B的作用力大小为(　　)

若$2+ai=b-i$，其中a，b∈R，$i$是虚数单位，则$a^2+b^2=$(　　)