—Who______ it be that is knocking at the door?—It ______ be Father, but I’m not sure.
—What ________his happiness all his life? —________what he has got.
—Do you know what made Susan so upset?I saw her weeping just now. —________giving away state secrets.
Weather ________,we'll go for a walk in the woods tomorrow.
It's a mistake to think of Florida only ________its tourist attractions.
To tell ________truth,the future is still a long way to go;we just arrived at ________crossroads,________new turning point;we will face a new challenge.