The scientist knew nothing about the matter, because he was always _________ himself in his study.

We had a big meal in a fine restaurant last Monday and the total cost ____________ $500.

Telling your sorrow to your friends will relieve the pain in your heart. All the words below have a similar meaning with the underlined word, Except ______.

There are a large number of plants existing on earth, however, very little _______ was made of them to feed us.

--- Only one of these books is worth _______.--- _______ is no wonder that you look so upset.