It’s interesting to contrast the British legal system ____ the American one.
The president of the university arrived yesterday, _____ the start of his short visit to China.
With more forests being destroyed, huge quantities of good earth _____ each year.
---- ____? ---- Maybe the possible solutions to the air pollution.
To my surprise, he was lost in thought then and not ____ of my presence at all.
When I met him the other day, it was the first time we ____ each other since we were at school.