单项选择题
A line on a weather chart connecting places which have the same barometric pressure is called an（）.
A.isotherm B.isallobar C.isobar D.isotope
单项选择题 A feature of an inflatable raft which helps keep people stationary in rough weather is（）.
单项选择题 A cold front moving in from the northwest can produce（）.
单项选择题 （）rain means it rains in some parts of the area.
