diminish和reduce

the pressure is reduced 10%
reduce的被动型态较为恰当

reduce

diminish v.指因为不断消耗，在数量方面缓慢减少，也指在素质或者价值的下降。

The supply of oil has diminished because of the war.由于战争石油的供应减少了。

reduce v.指人为地使某物在数量或重量方面的减少或降低。