This sentence has four underlined words marked a, b, c, or d. Identify the one that must be changed to make the sentence correct.We see lightning before we hear(A) the thunder, it causes(B) because sound travels more slowly(C) than light(D) is.

choose the word or phrase which best completes the sentence. The children wont go to sleep ____ we have a light on outside their bedroom. Option A: except , Option B: otherwise , Option C: unless, Option D: but, correct answer is: unless

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