Section 1: Fill in the Blanks (Past Simple vs. Past Continuous)
第一部分：填空题（一般过去时 vs. 过去进行时）
While I __________ (walk) home, it __________ (start) to rain.
答案： was walking; started
解析： "While"引导的是过去进行时（背景动作），主句是一般过去时（某一具体事件）。Randy __________ (not finish) his homework yesterday.
答案： didn’t finish
解析： "Yesterday"表示具体的过去时间，用一般过去时。Alice __________ (watch) TV when the phone __________ (ring).
答案： was watching; rang
解析： 过去进行时（Alice的背景动作）和一般过去时（电话铃响的瞬间事件）搭配使用。What __________ you __________ (do) when the accident happened?
答案： were you doing
解析： "When"引导一般过去时（事故发生的具体时间点），疑问句主句用过去进行时表示背景动作。While Belle __________ (study), her friends __________ (play) outside.
答案： was studying; were playing
解析： "While"引导两个同时发生的背景动作，均用过去进行时。Charles __________ (go) to the park last Saturday.
答案： went
解析： "Last Saturday"是过去的具体时间，用一般过去时。They __________ (wait) for the bus when it __________ (arrive).
答案： were waiting; arrived
解析： 等车是背景动作，用过去进行时；公交车到站是具体事件，用一般过去时。I __________ (fall) asleep while I __________ (read) a book.
答案： fell; was reading
解析： 过去进行时（读书的背景动作）和一般过去时（睡着的具体事件）搭配使用。The teacher __________ (ask) a question, but I __________ (not listen).
答案： asked; wasn’t listening
解析： "Ask"是具体动作，用一般过去时；"not listening"是背景动作，用过去进行时。When my parents __________ (arrive), we __________ (have) dinner.
答案： arrived; were having
解析： 一般过去时（父母到达的瞬间）和过去进行时（正在吃晚饭的背景动作）搭配使用。
Section 2: Choose the Correct Answer
第二部分：选择题
Which sentence is correct?
A. When I saw her, she was crying.
B. When I was seeing her, she cried.
答案： A
解析： "See"是瞬间动词，通常用一般过去时，"was crying"表示当时的背景情绪。We use the past continuous to describe:
A. A single completed action.
B. A background action happening at a specific time.
答案： B
解析： 过去进行时用于描述某一时间点正在进行的背景动作。__________ you __________ (watch) the match when your team scored?
A. Did, watch
B. Were, watching
答案： B
解析： 过去进行时（背景动作）和一般过去时（具体事件）搭配使用。When the train __________ (arrive), they __________ (wait) at the platform.
A. arrived, were waiting
B. was arriving, waited
答案： A
解析： 一般过去时（火车到站的具体事件）和过去进行时（背景动作）搭配使用。While I __________ (cook), someone __________ (knock) at the door.
A. cooked, was knocking
B. was cooking, knocked
答案： B
解析： "While"引导过去进行时（做饭的背景动作），主句用一般过去时（敲门的具体事件）。
Section 3: Correct the Errors
第三部分：改正错误
While Randy run, he fell into the river.
答案： While Randy was running, he fell into the river.
解析： 过去进行时（背景动作）需用 "was running"。Alice didn’t watching TV when I called her.
答案： Alice wasn’t watching TV when I called her.
解析： 否定句中，进行时需用 "wasn't watching" 而非 "didn't watching"。They was waiting for me when I arrived.
答案： They were waiting for me when I arrived.
解析： 主语是复数，助动词应为 "were"。When the bell was ringing, the students played outside.
答案： When the bell rang, the students were playing outside.
解析： "Ring" 是瞬间动词，用一般过去时；"play" 是背景动作，用过去进行时。I was walked to school when it started raining.
答案： I was walking to school when it started raining.
解析： 过去进行时需用 "was walking"。
Weak and Strong Forms of Was and Were
插入句子中强调的地方，用 强读形式（/wɒz/ 或 /wɜː/）；弱读的地方使用 /wəz/ 或 /wə/，常见于非重读部分。
例如：
Strong: "Was she at the meeting?"
Weak: "She was there, but she didn't say much."
