21.A waitress served us. She was very impolite and impatient. (WHO)
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22.Ms. Taylor is very gentle. I met her son on the stage last night. (WHOSE)
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23.I found a man's wallet. He gave me a reward. (WHOSE)
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24.The children sang and danced aloud all night. This kept their parents awake. (WHOSE)
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25.Teacher's Day is a special day. All the students show their gratitude to their teacher on that day. (WHEN)
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26. The last person who leaves the room must turn off the lights. (TO LEAVE)
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27. We have some picture books that your children can read. (TO READ)
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28. The woman who's talking to my mother has just returned home from London for several days. (TALKING)
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29.Can you see the notice which warns commuters not to turn left? (WARNING)
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30.The staff who did not complete their tasks before deadline yesterday explained their reasons to the boss. (NOT COMPLETING)
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