问题
选择题
下列关于抛物线y=x2+2x+1的说法中，正确的是[ ]
A.开口向下
B.对称轴是直线x=1
C.与x轴有两个交点
D.顶点坐标是（-1，0）
答案
答案：D
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下列关于抛物线y=x2+2x+1的说法中，正确的是[ ]
A.开口向下
B.对称轴是直线x=1
C.与x轴有两个交点
D.顶点坐标是（-1，0）
答案：D
任务型阅读。完成表格。 A solar-powered（太阳能动力的）plane has passed an important test on the way to travel around the world. The plane took off from an airport in Switzerland at 45km an hour. It slowly rose above the fields and into the sky. During the 90-minute flight, the plane did several turns. It climbed nearly l.6km above the countryside. "There has never been an airplane of that kind that could fly-never an airplane so big, so light, using so little energy," said Bertrand Piccard, a leader of the project. Engineers plan to test a night flight soon. They plan to travel around the world in that plane in 2012. "We want to fly it day and night with no fuel (燃料). " Piccard said. Piccard and the pilot Andre Borschberg will take the plane around the world. They will make a few stops to change places and rest after a long time in the air and to show off their aircraft. The plane flies at 70 kilometers per hour on average. That is faster than a bike. The pilots will keep the plane in the air for up to five days at a time.
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