A.each time the chart is changed B.once per month C.once per week D.daily
A.left,slightly behind him B.right,slightly behind him C.left,slightly in front of him D.right,slightly in front of him
A.perpendicular to the isobars in their warm sectors B.parallel to the isobars in their warm sectors C.parallel to the line of the cold front D.perpendicular to the line of the cold front