A UFO flew over my head while I was walking to ward the bus stop yesterday.

A UFO flew over my head shile I was walking toward the bus stop yesterday. A UFO flew over my head while I was walking to ward the bus stop yesterday. A ufo flew over my head while I was waking toward the bus stop yesterdayA UFO flew over my head while I was waking toward the bus stop yesterday 为什么是 A UFO flew ,不是 A UFO was flying呢?while引导的时间状语从句不是主从句都 I saw a UFO-over my head when I was walking toward the bus stop yesterday.中间填是fly flew 还flying the farmers were working on the farm a ufo flew over their A plane flew ____ the forest.A.over B.across the plane flew over the river in a f__________ flew over & flight over 有什么区别? When I was walking across the square,I saw a plane_______over my head.When I was walking across the square,I saw a plane_____ over my head.A) flies B) fly C) flew D) flown ONE FLEW OVER THE CUCKOOS NEST怎么样 with a strange cry they flew out through the palace-windows and away over the park and the forest flew an UFO还是 a UFO Jim saw a UFO lying over his head.(改为同义句) Jim saw a UFO lying over his head.(改为同义句) 关于while/when和see sb doing的问题1.Tom was sleeping_____ Mary was dancing to the music.A.since B.when C.as D.while这一题为什么用while不用when2.When I was walking along the road,I saw a bird_____ over my head.A.flies B.flew C.to fly D. my heart flew out of it's The people dived for cover as over their heads_______.A.the bullets flew B.did the bullets fly C.flew the bullets D.were the bullets flying选C每个选项解释一下