根据两个独立的小样本估计两个总体均值之差，当两个总体的方差未知且不相等时，使用的分布是（ ）。
— Is it better to be physically attractive or intelligent?
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— Do you prefer a portable or a clumsy 3D printer?
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Sometimes buyers only purchase some , tangible or intangible.
You can have eggs or hard-boiled.
As a rule, the buyer is responsible for a ship or booking the shipping space.
Goods are carried by several of transport--on road or rail, by sea or air.
— Hey, Derek, which do you think is harder to learn, marketing or designing?
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— I mean the best way is using your own mobile phone or computer to operate it.
people are no longer worried about whether their food is safe or not they enjoy a better life.
Every child is unique. Don’t him or her to others.
— May I suggest the sales start on or about October 1?
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Actually, buyers are the group of people want to buy certain goods or services.
Prices may change quickly if supply or demand .
—I think we can use two or more kinds of media together in an advertising campaign.
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— I wonder whether I could accept this discount or not.
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