One third of the country __________ covered with trees and the majority of the citizens __________ black people.
Bad habits, ______ formed(形成), are difficult to give up.
These natural parks are very important for preserving many animals, which would ______ run the risk of becoming extinct(灭绝的).
The girl didn’t know who ______ for the broken vase.
______ with the size of the whole earth, the highest mountain does not seem high at all.
-- How long do you think it will be ______ the bus arrives here? -- No more than five minutes.