_____he is only 8 years old,he knows more about science than his father.
You are sure to fail the test _________ you spend more time doing something helpful.
--There __________ a big lake near my house. But it’s gone now.--That’s too bad.
– Why do you like the boy so much, Sophia?– Because he is trying __________ best to catch up with others this term.
Paper is made ____________ wood. So saving paper is saving forests.
The light bulb is really __________ useful invention.