---- Where have you been all day?

---- I _____ some former classmates and I couldn’t get back until it was dark.    [ ]

A. have met

B. met

C. would meet

D. had met

制冷压缩机一段吸入压力往往是可调的，如后几段吸入压力不可调，将受到一段吸入压力、本段可吸入流量、本段蒸发量、压缩机末段吸入压力和排出压力的影响。