The aim of the trial operation of Shanghai Expo was to _______ problems, if any, so that the organizers could make changes accordingly.
.After they were given several terrible blows, the enemy did not _____ out after dark.
I thought it a pity __________ him to the tea party.
.A reward of 1,000 dollars will be given ________ can find the lost child.
.So often ______ in recent years that it has almost become a rule.
.The farmer who admitted ______ the tiger was severely punished.