题目

圆心距为3的两圆，半径分别是方程的两个根，则两圆的位置关系是（   ） A．相交       B．外离              C．内含               D．外切 答案：AHere are reports of three attacks. The three swimmers were attacked by sharks because they didn’t obey (遵守) the safety rules for swimmers.Rules for swimmers:A. Don’t swim at night.B. You are more likely to be attacked in warm water.C. Sharks are attacking by blood. Don’t swim with an open cut.D. It’s best to wear a swimming suit to match your skin colour. Sharks can see colours.E. If you see a shark,don’t be nervous. Try to! swim quietly, with even (平稳的) strokes(划水动作).Which rule didn’t each of the following swimmers obey?小题1: Report 1: Colin was swimming with two friendsvery late at night. He was attacked by a shark and died.小题2:Report 2: Ann was a very good swimmer. Shebought a new bright red swimming suit. She was swimming with some friends when a shark attacked her.小题3:Report 3: Jack was on holiday in Australia. Hecut his foot on the beach. He went swimming the same day and got at­tacked.