We mustn't condemn him on mere suppositions.我们不可全凭臆测来指责他.But as with many such suppositions in natural history, no one had ever tested it.博物学中虽然有许多类似的假设，却从没人对此考证过。We must make one of two following highly improbable ...

suppositions的音标：...

n.猜测( supposition的名词复数 )，推测，假定，猜想...