生产钢管的主要方法有自动轧管机、周期式轧管机、（）、顶管机组生产无缝钢管，用冷拔机生

关于呼吸的化学调节下列哪项是正确的（）。

A.外周化学感受器的主要刺激因素是PCO₂

B.在生理范围内随血中PaCO₂浓度增加而通气量增大

C.中枢化学感受器的主要刺激因素是缺氧

D.H⁺浓度变化较PaCO₂变化能更快影响通气

E.颈动脉体对pH和PaCO₂不敏感

Having my passenger in my car, I just wondered how I could _____the station since there was a traffic jam ahead.

A．make it to

B．reach for

C．speed up

D．see him off

She's having a lot of trouble with the new computer, but she doesn't know whom to________.              [ ]

A. turn to                        

B. look for

C. deal with                      

D. talk about

制冷装置中最普遍的故障是什么？