You have made a few mistakes in your composition but______, it's well written. [ ]

A. first of all

B. on the whole

C. on the other hand

D. so far

蝶形阀主要用在（）管道上。

A.大口径输送气体的

B.大口径输送掖体的

C.输送腐蚀性液体的

D.上水