________ with the size of the whole earth,the biggest ocean does not seem big at all.
33.A reward of 1,000 dollars will be given ________ can find the lost child.
32.So often ______ in recent years that it has almost become a rule.
31.The farmer who admitted ______ the tiger was severely punished.
30.They ______ be at home. You see, the door is locked from the outside.
29.Our English teacher had us all _______our names on a card.