16. The river, ______the bank are covered with trees, is very long.
I’ve kept up a friendship with a girl whom I was at school ________ twenty years ago.
In the experiment we kept a watchful eye ________ the developments and recorded every detail.
Books are the most important records we keep ________ man’s thoughts, ideas and feelings.
I don’t think it’s fair to judge a person ________ their clothes.
I am anxious about what notes he made in the back of his diary ________ things to mend or replace.