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Could it mean just one item( only one shirt), even though it is expressed with the plural be-verb('are')? and does it also mean many items(;jeans, pants, shirts etc.) at the same time, depending on the real conversational situation?

Am I right?
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I completely disagree with the second one.

I would never use "The clothes are in the dryer" to refer to one article of clothing.
Comments  
1. The word clothes is in the plural so you must use the plural 'are' to agree with its subject.

2. Yes, it can refer to one piece of clothing or many pieces of clothing.
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 BarbaraPA's reply was promoted to an answer.
Grammar GeekI completely disagree with the second one.

I would never use "The clothes are in the dryer" to refer to one article of clothing.

And besides, it isn't energy-efficient to do so. Emotion: shake

Such a waste! I just wonder what Greenpeace is going to have to say to you... Emotion: shake
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PhilipAnd besides, it isn't energy-efficient to do so.

Yeah, that did occur to me too.
Hi GG,

When I do my laundry I'm usually not concerned with how many pieces of clothing I put in the washer/dryer. From a strictly grammatical point of view, the clothes can't refer to only one article, I'll give you that.
"The clothes are in the dryer?"

The launrdy is in the dryer -ok, as laundry is a load of dirty clothes.

The clothes are in the dryer - incorrect, now clothes mean several pieces of garments. It can not be singular.
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