The key is that ____ full your schedule is,  only when  you try really hard ____ always

fit some more things  in it   [ ]

A. no matter how; can you    

B. no matter what; can you  

C. however; you can            

D. whatever; can you

安装在供热管道上的管件和保温设备应在（）进行。

A.水压试验前

B.试压合格后

C.闭水试验合格前

D.防腐验收合格后

E.闭气试验合格前