进行时的构成是:主语+be动词+目前分词~.
(目前分词的构成详见第六章)
1 目前进行时
I am watching TV now.
我正在看电视。
句型:主语+be(am,is,are)+目前分词~.
Look!Nancy is doing her homework
看!南希正在做作业。
They are cleaning their classroom.
他们正在打扫他们的教室。
2 过去进行时
He was1 walking in the park at that time yesterday
昨天那个时候,他正在公园散步。
句型:主语+be(was,were)+目前分词~.
I was watching TV then.
那时,我正在看电视。
When I came2 home, they were cooking3 in the kitchen.
当我进家时,他们正在厨房里做饭。