He ____ have finished his work; Otherwise, he would.not be enjoying himself by the seaside.
This photo of mine was taken _______ stood the famous Eastern Bright Pearl in Shanghai.
You should made it a rule to leave things _______ you can find them again.
In time of serious accidents, _______ we know some basic things about first aid,we can save lives.
The world is changing fast.I strongly believe that one will easily fall behind _______ he keeps on learning.
The traffic is very_______.It’s quicker to walk there.