1 If you ever decide to visit another world, Mars may be your best choice. 2Mars is much friendlier than the moon, Mercury, or Venus. 3 The nights on Mars are deadly cold, but a hot summer day would be comfortable. 4Mars also has weather, complex terrain, and signs that water once flowed over its surface. 5 Spacecraft have been visiting Mars for almost 40 years, and the pace has picked up even more recently. 6 Spacecraft have gone into orbit around Mars to photograph and analyze its surface, and six spacecraft have landed.

1. Which sentence is the topic sentence? a. Sentence 1

b. Sentence 2

c. Sentence 6

2. What is the topic? a. Living on Venus

b. Living on Earth

c. Living on Mars