The boys were singing while the girls were dancing last night.为什么用were singing.不能用sang吗?

Were were the boys( )那时 The boys were playing the football 修改错误项 the boys were t__ in the burning building The boys were very unhappy because the teacher The boys were in the playground.改一般疑问句 ____the boys in the playground?___No__ __. supposed how the boys to home were go The boys were singing while the girls were dancing last night.为什么用were singing.不能用sang吗? The participation of the boys (was,were) essential to the success of the ex I noticed that the boys were making faces in class.I _____ the boys _____ _____ in class. both of the boys were from Sydney.(否定句)_____ _____ the boys _____ from Sydney.非常急! （ ）The boys who ________ the loudest were the winners.A.shouted B.shouting C.was shouting D.were shouted（ ） The boys ________ the loudest were the winners.A.shouted B.shouting C.was shouting D.were shouting The boys were in the playground .(改为一般疑问句,并回答)The boys were in the playground .(改为一般疑问句,并回答)_______ the boys in the playground No,_____ ______ 128 the missing boys were last seen___near the riverplaying to playwhy? The boys was making a noise while the were sleeping last morning.（此句两处错） lesson to end是什么用法the boys were inting for the lesson to end The missing boys were last seen _____ near the river.为什么填playing “ing”形式? 英语翻译while we boys were working hard in the garden.out sisters were enjoying themselves in the sitting room. The boys were walking down the street.(就画线部分提问) （ ） （ ）the boys （ 划线部分为：walking down the street