—Do you know ________ Simon is?—I met him in the school library just now. He may be still there.
When the father heard from his son from abroad, he became ________.
We were all ________ favor of this plan after we discussed for about two hours.
Frank looks very worried today. There must be ________ wrong with him.
As students, we should work hard and do ________ best to realize our dreams.
Some naughty boys like to play ________ trick on their classmates on April Fool’s Day.