The study of natural history is not something to be left to biologists. In fact, their capacity __________ the time they can spend away from their offices is very limited.
No sooner ________in the distance ______a storm began to pour.
The CDs are on sale!Buy one and you get ______ completely free.
It’s no use____ that you didn’t know the rules.
. At a rough estimate(估计), Nigeria is ____ Great Britain.
. In face of _______ failure, it is the most important to keep up ________ good state of mind.