Bài tập 1: Chọn đúng thì của các câu sau (quá khứ đơn và quá khứ tiếp diễn): 1. Alice saw/ was seeing the accident when she was catching the bus. 2. What were you doing/ did you do when I called? 3. I didn’t visit/ weren’t visiting my friends last summer holiday. 4. It rained/ was raining heavily last July. 5. While people were talking to each other, he read/ was reading his book. 6. My sister was eating/ ate hamburgers every weekend last month. 7. While we were running/ ran in the park, Mary fell over. 8. Did you find/ Were you finding your keys yesterday? 9. Who was she dancing/ did she dance with at the party last night? 10. They were watching/ watched football on TV at 7 p.m. yesterday