By Julia MacNair Wright

Can you tell what causes day and night, seasons and years, tides and

eclipses? Why is the sky blue and Mars red? What are meteors and

shooting stars? ¶ These and a thousand other questions are answered in

a most fascinating way in this highly interesting volume. Few books

contain as much valuable material so pleasantly packed in so small a

space. ¶ Illustrated.

Health: How to get it and keep it. The hygiene of dress, food, exercise, rest, bathing, breathing, and ventilation. · 第 71 / 88 题