The game is boring, I don’t like it .
Trees can stop the sand _____ towards the rich farmland in the south.
This is the most beautiful butterfly I have _____ seen in my life..
—What are you reading about?—It’s about the one-child policy. It says that the policy has_____ controlling the population in China.
Maria has _____ trouble _____ math, so she often asks her math teacher for help.
The rivers in Changshun are clearer than _____ in Wuhan..