Viết lại câu với because of

28. Mary didn’t go to school yesterday because she was sick.>> Because of
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29. She went to bed early because she felt tired. >>Because of
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30. Margaret stayed at home because her mother was sick.>> Because of
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31. I couldn’t do the test because it was difficult.>> Because of
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32. I couldn’t read the letter because it was dark.>> Because of
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33. I can’t study because it is noisy.>> Because of
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34. The train come late because it was foggy.>> Because of
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35.  The train was late because the fog was thick.>> Because of
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