–I’d like to buy a new CD player.     –Well, we have several models ________.

As we know, penicillin became the greatest drug of the 20th century, ______ millions of lives.

What kind of mistakes do you want to avoid ____full marks in your test?

He was thinking about the problem when an apple fell off the tree, _______ him right on the head.

______ money , it remains to be seen whether we can put the idea into practice.