哪颗行星被称为红色星球？

Which planet is called the Red Planet?

Mars is sometimes called the Red Planet. This planet is about half the size of Earth. The surface of Mars is covered with rock and red dust made from iron. Mars has huge volcanoes and craters. A year on Mars lasts 687 days, and one day is 24 hours and 37 minutes.

完整讲义，尽在微信公众号：
宝妈乐贝成长日记