A. To have a place for soldiers to live. B. To be able to trade with people on the other side of the wall. C. Because soldiers needed help during attacks. D. Because it was very safe to live close to the wall.
A. 中央前回和中央旁小叶的前部 B. 中央后回和中央旁小叶的后部 C. 颞上回 D. 颞横回
A. 红色 B. 白色 C. 绿色 D. 蓝色
A. 远视眼 B. 近视眼 C. 散光眼 D. 正视眼
A. 柱细胞 B. 指细胞 C. 螺旋器的毛细胞 D. 螺旋神经节细胞
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