He said that not until the heavy snow blocked the express _________ how serious the weather was.
_______ difficulties we may com across, we'll help one another to overcome them.
So little known _____ that soldiers had to ask for a guide.
This monument was built in honor of the scientist who was believed ______ the first telephone.
I have kept that picture ______ I can see it every day,as it always reminds me of my university days in London.
I wonder what notes he made in the back of his diary ______ things to mend or replace.