21.Have you heard_____report? People with______good knowledge of engineering are in great need in the job market.
He ____ down his life for the cause of freedom.
My most famous relative of all, ____ who really left his mark on America, was Rob Sussel, my great-grandfather.
Did ____ on time make her teacher angry?
---Next Monday is my birthday. ---Is that so? ____ ---Thank you.
What surprised me was not what he said but ____ he said it.