_______ difficult and challenging the task may be, we must finish it on time, because there is a possibility _______our work will go down in history.
The stubborn boy didn't _____ so that he missed the chance.
You'd better make a mark _____ you have any questions.
I like ______ of the two stories, for this story is _____ than that one.
Our English teacher _____ by the teachers and students.
Only a fool enjoys _____ in public.