According to scientists, our mental abilities begin to _____ from the age of 27 after reaching the highest level at 22.
---Where’s the little elephant? ---It’s said it ___ in the hospital.
She wondered what use she would _______ this chance.
_____ learn more knowledge, the students stay at school on Sunday.
The two companies are competing ___ each other to get into the Chinese market.
If you don’t want to choose the thinner one, ___.