一．现在进行时
现在进行时(present continuous tense)表示现在正在进行的动作或存在的状态。
谓语： be+doing （be 为am, is, are,）
例如：
1. What are you doing?
你现在在干什么?：
2. I am singing a song.
我在唱歌。
3. They are discussing how to sell these goods.
他们正在讨论如何销售这些商品。
现在进行时的用法：
①现在进行时表示现在正在进行的动作,由"to be+现在分词"构成。另外,"系动词+介词或副词"也表示进行时的意义。例如:
What are you doing. The bridge is under construction.
②表示感觉、愿望和状态的某些动词(如have,be,hear,see,like等)一般不用进行时;
③always,constantly,frequently,continually,forever,all the time等连用,表示赞叹、赞扬、厌恶、不满等情感。例如:
He is always thinking of others.
二．过去进行时
过去进行时(past continuous tense)表示过去某一时刻或某个时间内正在进行的动作。
谓语： be+doing （be 为was, were,）
例如：
1. I was watching TV at nine yesterday evening．
昨晚九点我正在看电视，
2. When I saw her she was talking.
我看到她时她正在谈话
3. He was having a meeting from 2 to 4 yesterday afternoon.
他昨天下午2点到4点在开会。
过去进行时的用法
①表示过去某一时刻或某一段时间内正在进行或持续进行的动作。这一特定的过去时间,除有上下文暗示外,一般用时间状语表示。例如:a moment ago,then,at that time,last year,at 9 o'clock yesterday,all morning,when I came in等。例如:
I was drawing a horse when the teacher came in. He was mending his bike at ten o'clock yesterday.
②表示按计划、安排过去某时即将发生的动作,但仅限于come(来),go(去),leave(离开),start(出发)等少量动词。例如:
She wondered whether he was coming back for supper. He told me he was leaving the next day.
③表示过去某一动作发生的背景。例如:I don't think Jim saw me;he was just staring into space.
④表示过去频繁发生的习惯性动作,带有"赞扬"或"责备"等感情色彩。例如:
He was always changing his mind. The two brothers were frequently quarreling.
⑤表示婉转的口气。例如:I was hoping you could help me.
温馨提示：答案为网友推荐，仅供参考