Once you’ve written down all your goals, both large and small, the next step on your journey to success is to activate the creative powers of your subconscious mind by reviewing your list two or three times every day. Take time to read your list of goals. Read the list one goal at a time. Close your eyes and picture each goal as if it were already accomplished. Take a few more seconds to feel what you would feel if you had already accomplished each goal.

流量工作时，过长的引压管会使测量准确度下降，引压管的距离一般不超过（）。

A、16m

B、30m

C、20m

D、50m