• 動詞改為現在分詞(V-ing)的方式

1. 直接在動詞後加 ing
   如 work-->working / play-->playing

2. 字尾為不發音的e，去掉字尾 e再加 ing
   如 ride-->riding / exercise-->exercising

3. 短母音加單子音，重複字尾子音再加ing
   如 mop-->mopping / sit-->sitting

4. 字尾為c，且發音為[k]，字尾需多加一個k再加ing
   如 picnic-->picnicking

5. 字尾ie，ie改成y再加ing
   如: die-->dying / lie-->lying

• 描述過去發生的兩個動作，這兩個動作時間部分重疊，其中一個持續進行的動作被另一個短暫的動作打斷，持續進行的動作用過去進行式(動作執行期間長)，打斷的動作用過去簡單式(動作執行期間短)表達。
  [記憶點1:早發生晚結束的動作->進行式；晚發生早結束-->簡單式]
  [記憶點2:執行時間較長的動作-->進行式；執行時間較短的動作-->簡單式]
  例如:
  I was taking a nap when he called yesterday afternoon. [睡午覺/打電話這兩個動作，睡午覺比打電話更早開始]
  I was having dinner when she came to visit. [吃晚餐/友人拜訪這兩個動作，吃晚餐比友人拜訪更早開始]

1. 過去進行式的動詞形式為 was / were + Ving
   例句
   This time last year, he working as a chef in Taipei. (X)
   This time last year, he was working as a chef in Taipei. (O)
   
   I’m working on my project when he called.
   I was working on my project when he called. 

2. 動詞字尾已經有 e時，直接加 -ing
   例句
   We were haveing dinner at six yesterday. (X)
   We were having dinner at six yesterday. (O) 

3. 單音節動詞以一個母音字母加一個子音字母結尾，則重複字尾子音字母後，再加 -ing
   例句
   Allen was siting on the sofa and watching TV when I arrived. (X)
   Allen was sitting on the sofa and watching TV when I arrived. (O)

以下是進行式與簡單式的比較

4. begin和leave都是瞬間動詞，不適合使用進行式。
   Rob left his house at 7 30 A.M. and was beginning to walk to school.(X)
   Rob left his house at 7 30 A.M. and began to walk to school.(O)

5. take a walk先開始且進行到一半的時候才發生run into (偶遇)這個動作，因此較早發生的take a walk應使用進行式，run into用簡單式。
   Linda was running into her neighbor Mr. Wong when she was taking a walk in the park. (X)
   Linda ran into her neighbor Mr. Wong when she was taking a walk in the park. (O)

6. cross  the street(過馬路)進行到一半才發生車子撞到(hit)我這件事情，因此較早發生的corss the street應使用進行式。
   I crossed the street when the car hit me.(X)
   I was crossing the street when the car hit me.(O)

7. wake up是瞬間動詞，不適合使用進行式。另，應是先開始下雨我才醒來，因此rain下雨是用進行式，wake up醒來則是簡單式。
   When I was waking up this morning, It was raining.(X)
   When I woke up this morning, it was raining.(O)

8. 時間副詞8 P.M. last night是個時間軸上相當短暫的時間副詞，與study讀書所執行的時間來相對來說較短，因此study應該使用進行式。
   A: What were you doing at 8 P.M. last night?     B: I studied.(X)
   A: What were you doing at 8 P.M. last night?     B: I was studying.(O)

9. suddenly(突然間)這個副詞通常修飾中途突然插入的動作，因此feel應該是比study較晚發生且study持續時間較長，故study應該使用進行式，feel用簡單式。
   While I studied, I was suddenly feeling sleepy.(X)
   While I was studying, I suddenly felt sleepy.(O)

10. the power goes off (停電)為中途突然插入的動作，是看電視看到一半發生的事情，watch TV應該是更早開始且持續較長的動作，故watch TV應該使用進行式，go off用簡單式。
    We watched TV when the power was going off.(X)
    We were watching TV when the power went off.(O)