18. The owner of Steele’s Grocery in Osage, Ohio, saved $600 monthly on heat during the winter by putting all his refrigerator air compressors together in an insulated compartment, then installing two fans and a duct that carried waste heat from the compressors into the main part of the store. (A) then installing two fans and a duct that carried (B) then he installing two fans and a duct that carried (C) then two fans were installed with a duct that carried (D) installing two fans, and then carrying through a duct (E) installing two fans, and a duct carrying

then到底是做甚么词啊 谢谢

选a吧，then是副词，然后啊

putting与installing平行，

that 指代fans and duct

对吗

我觉得2楼说的不对。then是副词没错，但是putting和installing不是平行，因为then是副词而不是连词，所以二者无法平行。这里的installing应该是做伴随。