were planted,have planted,have been planted有什么区别?

they have/were planted last year.哪个正确以及区别. i planted tree yesterday 和i have planted tree yesterday 的区别, mang trees have been planted by people the how many trees have you planted? The flower I ( ) grown up.A.planted has B.planted have C.has So far we ( ) about 1000 trees. a.planted b.have planted c.h 高中英语反义疑问句These trees must have been planted three years ago, 一道英语选择,These trees must have been planted three years ago,__ A lot of flowers have been planted in the garden.用一般过去时或一般现在 _________ trees have been planted these years. A．Million B．M many trees and flowers have been planted in recent years.the 请说明理由1,these trees must have been planted three years ago.__