I. MAIN IDEA QUESTIONS: FIND THE TOPIC SENTENCE The main idea of a reading passage is in the topic sentence, which is usually near the beginning of the passage, pointing out the authors main idea of the whole passage. Above all, the topic sentence effectively sums up the main idea. Passage: Many people think of heat and sand when imagining a desert, but surprisingly, Antarctica is technically the largest desert on Earth. A desert is defined as a place that gets an extremely low amount of rainfall. A land of cold and ice, Antarctica gets less precipitation than any other area in the world. Totaling over thirteen million square kilometers, the Antarctic desert is almost four million square kilometers larger than the world-famous Sahara desert. 84. Which title best summarizes the passage? A. Lands of Heat and Sand C. The South Pole and Antarctica B. The Earths Many Deserts D. The Vast Desert of Antarctica