It is so difficult a problem that _____ student in this class _____ work it out.
The car ______ at the present speed until it reaches the foot of the mountain at about ten o’clock tonight.
Though ______, many laws of nature exist.
_____, I couldn’t find a solution to the problem.
The servant did _____ she could ______ the revolutionary.
If you ______ the medicine you ______ better now.