You can only be sure of _____ you have at present; you cannot be sure of something _____ you might get in the future.
I know nothing about the young lady ___________ she is from Beijing.
Sandy could do nothing but _________ to his teacher that he was wrong.
--The prison was ___________ fire last night. --Someone must have set fire___________ it.
The __________ is just around the corner and you won't miss it.
__________ she couldn't understand was__________ fewer and fewer students showed interest in her lessons.