下图表示暖锋天气的示意图是 ( )
答案:A
暖锋是暖气团主动向冷气团方向移动,暖气团沿冷气团徐徐爬升,暖气团势力强,冷气团被迫后退
It's common knowledge that black tea ________ in China more than 600 years ago.[ ]
A. is invented
B. was invented
C. invents
D. invented
热痉挛主要是由于哪个方面的障碍所致
A.心血管B.神经C.消化D.体温调节E.水盐代谢