Dark clouds are a ___of rain while a smile a ____of friendship.
______ relation between China and Russia has developed steadily since Vladimir Putin was re-elected______ president.
The precious paintings were hopelessly______ by long exposure in the cold, damp garage.
_______ is no possibility________ the engineer can complete the project within two weeks.
______ the crown of the second season of The Voice of China, Liqi devoted himself to practicing singing.
The students took the trouble _____ all the ______ leaves away.