Jetstreams（）
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
避难硐室的英文表示正确的是（）
A. refuge chamber
B. tefage chamber
C. aefuge chamber
D. befuge chamber
井下基地的英文表示正确的是（）
A. underground rescue base
B. undreground tescue base
C. undrerguond iescue base
D. undergruond wescue base
微信支付 
支付宝支付