When I passed by the station,I saw the accident _____.A.happening B.happens C.happened S.happen 怎么选

I heard someone open the door when I passed by 改错 when i passed the river为啥用passed. 同义句转换：When I passed by,I saw them playing football.（改passed by) .When I passed by his door,I heard him _____________. I heard them giggle when I passed by the girls.请对本句 I heard them giggle 进行语法分析。 填入适当形式的词语 I found some kids (dance) in the classroom when I passed by. I found a man ____ (lock) the door when I passed by.填入适当形式的词语 i heard someone___(cry)in the next room when i passed by 什么理由i heard her___(cry)in the her room last night。又是什么？ I saw a little boy trying when i passed the park passed能改成passing吗? When I passed by the station,I saw the accident _____.A.happening B.happens C.happened S.happen 怎么选 I heard her in her room when I passed by. Ato singI heard her in her room when I passed by.Ato singBsingingCsingDsings the studends 这是要选的空 the art festival when i passed by their school.a.celebrate b.were celebrate c.will celebrate d.have celebrated .When I passed by his door,I heard him _____________.A、singB、 第3 I,passed,heard,her,when,I,singing,by.(连词成句） The dog bit him on his leg when he passed by.his 为何改the playing,were,they,childern,by,when,volleyball,passed,watching,their,I连词成句 The dog was chasing the cat when I passed the garden变一般疑问句passed 需要变回原形吗? When I passed the driving test,I thought I was the_____(luck)person in the world.