Upvc
abbr. unplasticized polyvinyl chloride 未增塑聚氯乙烯
🗣️ 情景例句
Would you like to sign the contract now?
你现在要签这合同吗？
He has been to America.
他去过美国。[曾经有过的经验]
Mary is still writing letters. She's been writing letters all day.
马力还在写信，她写了一整天的信。