把people place litter baskets under the trees改为被动式
问题描述：
把people place litter baskets under the trees改为被动式
people place litter baskets under the trees改为现在完成时、一般过去式、一般将来时的被动语态
答
现完：Litter baskets have been placed under the trees by people.
过去：Litter baskets were placed under the trees by people.
将来：Litter baskets will be placed under the trees by people.
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望采纳~