已知2^a=3^b=m，ab≠0且a，ab，b成等差数列，则m=（　　）

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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请根据上述实验过程解答下列问题：

如图所示，位于斜面上的物块M在沿斜面向上的力F作用下，处于静止状态，则斜面作用于物块的静摩擦力是（   ）

①欣欣便利店员工上午____时上班。
②欣欣便利店全天营业时间是____小时____分。
③13:30—17:00也就是下午____时____分到____时。