长城总长约为6700010米,用科学记数法表示是 ( ).(保留两个有效数字)
A:6.7×105米
B:6.7×106米
C:6.7×107米
D:6.7×108米
请根据下列气温和降水变化图,完成下题。
点M(-sin60°,cos60°)关于x轴对称的点的坐标是( )
She ________ his number in the phone book to make sure that she had got it right.