第一节（共15小题；每小题2分，满分30分）
阅读下列短文，从每题所给的四个选项中，选出最佳选项
（A）
Imagine looking for your lost dog. You step into a cave（洞穴）. But instead of the dog, you find beautiful cave paintings. You see paintings of horses, deer, and bison that are drawn in black, brown, red and yellow. Your first question would probably be "Who did this?"
