Drop tube for head- and cross

Drop tube for head- and cross exhausted tube and flair tube for GLS是什么意思? 什么是drop-tube? If you drop down heavily and your head is down.的翻译谢谢 翻译一下If you drop down heavily and your head is down. 英语翻译if you drop down heavily and your head is down,this coul leave the tube for one 英语翻译Temperature cross in single multi-tube pass shells shoul tube head to和head for 英语翻译Pls check and adv the drop dead qty and date for pushing 什么是drop and continue