All the apparatus______ before the experiment began.1.have been tested 2.had been tested

来源：学生作业帮助网 编辑：作业帮 时间：2024/10/05 22:52:13
All the apparatus______ before the experiment began.1.have been tested 2.had been tested
xN@_e@dݐ$QL6CBZL@~R%h@10wtX vq{SEOe`jin?P 8𹎍cZl7Q0

All the apparatus______ before the experiment began.1.have been tested 2.had been tested
All the apparatus______ before the experiment began.1.have been tested 2.had been tested

All the apparatus______ before the experiment began.1.have been tested 2.had been tested
选择2 had been tested
before引导时间状语 表示过去某一时间或动作之前已经发生或完成的动作或存在的状态.
句意：在试验开始前、所有器械已经被检查过了
“检查器械”是发生在“实验开始”前,
began是用的过去式、所以“检查（test）”这个动作要用过去完成时 表示“过去的过去”

all the all the all the all the all the All the the all all the time all the All day just all the all the right all around the all around the thanks all the thankyou all the same all around the world 英语翻译all the girl power all the all the way