I dropped ________ and it wetted the carpet in the sitting room．

All that can be done ____.

American women were _____ the right to vote until 1920 after many years of hard struggle.

Liu Xiang achieved his __________ to become the first man to cover the 110-meter hurdles in less than 12.91 seconds.

Finding information in today’s world is easy．The_______is how you can tell if the information you get is useful or not。