CCBⅡ克诺尔制动机与DK—1型制动机相比设有制动区，具有特点

A. the boundary between polar air and equatorial air
B. the boundary region between the two monsoons
C. the region between the two trade wind systems centred on the heat equator
D. a region of calm winds and layer type clouds with much haze

A. caused
B. not caused

A. are caused by a large difference in mean temperature in the horizontal
B. are located above the tropopause
C. only occur in the troposphere
D. have a speed in excess of 80 kt

A. refuge chamber
B. tefage chamber
C. aefuge chamber
D. befuge chamber