据史料记载，洪武十七年九月十四日到二十日，送到皇宫的奏章共1160件，涉及3291件事情，皇帝平均一天要处理411件事。导致这一现象的主要原因是(  )

A

(Mr. Smith and Bob are in a store.)

Man: What can I do for you?

Mr. Smith: I want a sweater for my son.

Man: What color does he like?

Mr. Smith (to Bob): What color .do you like?

Bob: I like blue.

Man: Do you like this one?

Bob: Yes. It looks nice. How much is it?

Man: 80 dollars.

Mr. Smith: It's too pricey.

Man: Look at this black one. It's on sale. It's only 30 dollars. This green one is 50, and that brown one is 40.

Mr. Smith: Mmm…… I think the black one is nice, too.

Bob: But I don't like black. I like blue.

Mr. Smith: OK, we'll take the blue one.

Bob: Thank you, Dad.

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下列各算式中，合并同类项正确的是（   ）

①游戏厅   ②公园   ③影剧院   ④贸易集市