________in the heart of Toronto is the Canadian National Tower , which is often called the CN Tower for short.

I went back to the cinema to look for my keys, only __________. 

 It’s necessary to be prepared for a job interview.              the answer ready will be of great help.

I was chatting on the Internet last night when I smelt something   in the next room．

 I found the cat____ under the bed, who had caught a mouse.