With the word "PM2.5"______ heard and seen in our life, people become more and more concerned about air pollution.
Please keep______ secret that he' s decided to give up his present position.
It was a pity that the great writer died _________his works unfinished.
The girl ________ name was Diana sat next me.
----Do you know our hometown at all? ----No, this is the first time I _____ here.
“How long do you suppose it is _______ he left for Japan?” “No more than half a month.”