Which of the following books was written by Charles Darwin?
A. The Sea Around Us
B. The Edge of the Sea
C. The Origin of Species
D. Slilent Spring
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Rachel Carson decided that she wanted to be a writer when.
A. she was very young
B. she was in college
C. she became a teacher
D. she became famous
Silent Spring is a book in which the author calls for man's attention to the protection of the environment as well as the human beings themselves.
A. 对
B. 错
砂浆沉入度值越大，表示新拌砂浆的流动性。（填“越大”或“越小”）
变压器空载电流相位（）主磁通相位α角度。
A. 超前
B. 滞后
C. 大于
D. 小于
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