萬金油句式。 主語+ was / were +動詞-inging形式+其它
肯定式：主語+was/were+動詞-ing (+其他).
例如：I was swimming at that time.
否定式：主語+wasn’t/weren’t +動詞-ing (+其他).
例如：They weren’t listening to music at ten yesterday morning.
疑問式： Was / Were+主語+動詞-ing (+其他)?
其肯定回答為：Yes, 主語(人稱代詞)+ was / were.；
否定回答為：No, 主語(人稱代詞)+ wasn’t / weren’t.
例如：—Was Joe reading at the time of the rainstorm?
—Yes, he was. / No, he wasn’t.
過去進行時由“was / were +動詞-ing”構成，表示在過去某一時刻或某一段時間正在進行的動作。常與過去進行時連用的時間狀語有at eight / nine …… (o’clock) yesterday morning, at that time，from eight to ten yesterday morning等。
例如：We were playing basketball at nine yesterday morning.
Susan was taking an acting lesson from one to three yesterday afternoon.
2. 由when引導的時間狀語從句，若主句的動作正在進行，這時從句的動作發生了，則主句用過去進行時，從句用一般過去時。
例如：What were you doing when the accident happened?
3.由while引導的時間狀語從句，當從句的動作正在進行，這時主句的動作發生了，則從句用過去進行時，主句用一般過去時。若主從句的動作在過去同時進行，則主從句均用過去進行時。
例如：While my mother was cooking, I was doing my homework.
While Jenny was having dinner, her father came back.
拓展難點
when和while都可表示“當……的時候”, 引導時間狀語從句。兩者在過去進行時中的用法不同。
1）主句的動作是持續性的，而從句動作是短暫性的，此時用過去進行時引導時間狀語從句，主句用when時態，從句用一般過去時態。
例如：I was walking to school when I saw a cat in a tree.
When Sally arrived home, her mother was cleaning the house.
2）主句的動作是短暫性的，從句的動作是持續性的，此時用while引導從句，主句用一般過去時態，從句用過去進行時態。
While I was sleeping in the bedroom, someone knocked at the door.
David fell while he was riding his bike.
3）主句和從句的動作在過去的某時刻或某段時間同時發生, 而且動作都是持續性
的, 此時用while 引導從句, 而且主句和從句都用過去進行時態。
例如：While Andy was waiting for the bus, he was reading a newspaper.
He was cleaning his car while I was cooking.
句型理解
positive+（陳述句）
negative+（否定句）
question+（疑問句）