1 think we'd better keep to the subject, ______we'll waste our time.
All possible means ____, but nothing can prevent the buildings ____.
Gun control is a subject _________ Americans have argued for a long time..
Such a grammar mistake is _____ among the beginners of English study. 5.
Knowledge and learning are important if we want to be successful, but they may also ______ our thinking.
--- We can give you a ride into town. --- ________ Thank you.