Farmers here _________keeping the soil rich and _________diseases.
Each girl present at the party was wearing a flower in the hair, which _______ their beauty.
He decided to _________ the club for old men and play chess there.
According a recent report, there are _________ to be 1.35 billion people in China in 2017.
In the old days, some wealthy people killed animals just for the ______ of it.
Xiao Li was about to cheat in the exam ________ the teacher came up, smiling to him.