题目

Do you want to see the effects of global warming? Then head north. Recent studies indicate that the North Pole could be underwater during the summer in less than 10 years, instead of coated in thick sea ice. But seeing the Arctic terrain （地带） up close isn’t easy, unless you’re handy with a dogsled. Steger is going to take all of us there．Steger, 64, is a great polar explorer. He was the first person to make a dogsled trip to the North Pole, and is also a devoted environmentalist who was early to ring the alarm bell on global warming.Steger is about to lead a team of six young adv如果两条平行直线被第三条直线所截得的8个角中有一个角的度数已知，则（ ）A．只能求出其余3个角的度数B．只能求出其余5个角的度数C．只能求出其余6个角的度数D．只能求出其余7个角的度数