—Kathy and her sister are so alike.—I can’t tell one from ____.
We made plans for a visit but _____ difficulties with the car prevented it.
He didn't _____ what I read because his mind was on something else.
Scientists have to work hard to keep _____ with modern discoveries and developments.
She _____ the temptation to buy a coat she could not afford.
He put in a special _____ for an extra day's holiday so that he could attend his daughter's wedding.