1. I/my room/they/in the cafe
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I [am] in my room. They [are] in the cafe.
2. You/my car/they/Hello
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You [are in] my car. They say Hello.
3. He/she/in the park yesterday
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He [was] in the park yesterday.
4. They/fly/to London/on the plane
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They fly to London on the plane.
или: They are flying to London on the plane.