He will come to understand your efforts sooner or later. It's just a matter of_______.
She has finished typing but she doesn’t know _______ next.
The kind teacher devoted all her time she had ___________ her students.
— It’s dangerous to walk across the street carelessly. — You’re right. We can’t be careful while crossing the street.
It’s quite clever ________ you _______ out the problem.
---Tom, you play football in the street. ---Sorry, Ido it again.