In order to increase the sales of some goods, customer __________ need to be studied.
Jennifer is gaining a lot of __________. Now she looks fatter than she was in the past.
In order to be _____________ in studying English, one thing that children can do is to review English vocabulary regularly.
Nowadays, we should help to save the world. The ____________ is some ways that we can do: growing more trees, using less CFCs, and using car-pools.