深海R蔚蓝
您好，新概念英语第一册第143课的课文中的被动语态有：
... which is surrounded by beautiful woods.（be surrounded by 是被动语态：一般现在时被动语态）
Visitors have been asked ...（have been done 是被动语态：现在完成时被动语态）
Litter baskets have been placed under the trees ...（have been done 是被动语态：现在完成时被动语态）
... and the ground was covered with ...（be covered with 是被动语态：一般过去时被动语态）
... will be prosecuted!'（will be done 是被动语态：一般将来时被动语态）
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