问题描述:
-Have you heard of Earth Day?
-Yes.The first Earth Day _____ in 1970to educate us to protect our planet.()
A.celebrates
B.celebrated
C.is celebrated
D.was celebrated
-HaveyouheardofEarthDay?-Yes.ThefirstEarthDay_____in1970toeducateustoprotectourplanet.()A.celebratesB.celebratedC.iscelebratedD.wascelebrated
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