Questions 1-2 are about the following passage.

    Mars is the fourth planet from the Sun and the seventh largest planet in our Solar System. It is sometimes called "the Red Planet" because the iron oxide on the surface makes it look red. In many ways, Mars is very similar to Earth. It has volcanoes, valleys, and deserts just like Earth. Because of these similarities, many scientists believe that the surface environment of Mars may not always have been so hostile to life. Some of them think that water exists on Mars, which would make it possible for life to exist there.

    Mars' surface area is about the same as the land surface area of Earth. There are plains made from lava flows, and the highest known mountain and largest known canyon in the Solar System are on Mars. The mountain, Olympus Mons. is almost 3 times as tall as Mount Everest. The canyon, called Valles Marineris, is 4,000 kilometers long, 200 kilometers wide and up to 7 kilometers deep.

    Mars has a lot of impact craters, which are the result of large objects hitting the planet's surface. Therefore, scientists argue that very large objects hit Mars about 4 billion years ago. This theory would explain why Mars' surface looks the way it does. Mars is located very close to the asteroid belt, which lies between the orbits of Mars and Jupiter, so it is more likely to be hit by asteroids. However, Mars still has fewer craters than the Moon. This is because Mars has a more substantial atmosphere than the Moon.

    Scientists know about Mars' surface because they have been able to send spaceships with high-resolution cameras to Mars, as well as robots to collect rock samples. Still, there is much more to fmd out. Scientists hope to visit Mars someday.