Sentence:  Rain of near cloudburst proportions had <WSD>fallen</WSD> for three full days and it was still raining on the morning of Friday , November 4 , 1927 , when officials of the Post Office Department 's Railway Mail Service realized that their distribution system for Vermont had been almost totally destroyed overnight . 
Meaning of the word marked with <WSD> tags:  descend in free fall under the influence of gravity