Swimmers must be very strong in order to build up speed because of the high resistance of the water. Runners, ____, must struggle against the heavy resistance of the air and ground.
Bill suggested ________ a meeting on what to do for the Shanghai Expo during the vacation.
_________many times, he finally understood it.
This morning, I rushed to the library, only ________ that its door was still locked.
_______ with so much trouble, we failed to complete task on time.
What we should be thinking about now is how to make up for the lost time, not who is _______.