---How many students are there in the playground?  ------             .

Low-carbon life is of great benefit to improve the world environment. _____ can be enjoyed from it until you have a deep understanding of it, though.

The manager believes that prices will rise by more than        4%.

Jack has three sons, and both of _______ are studying in China.

- What shall we do this weekend?  - You can go swimming, hiking, or_______ else you enjoy doing.