________our earth，or else it will be no longer fit for us to live on.
| A．Protecte | B．To protect | C．Protecting | D．Protect |
The reason ____he was late was ____he had taken a wrong bus.
| A．why; because | B．for; because of | C．why; that | D．for; that |
Did John ____ the general cleaning yesterday afternoon?
| A．join | B．attend | C．take | D．take part in |
He was educated at a famous university, _____ he went abroad and settled there.
| A．after that | B．after which | C．in which | D．in that |
The 29th Olympic Games ____ in Beijing in 2008.
| A．was held | B．will be held | C．has been held | D．is being held |
The flowers don’t need too much water; you can just water them _____.
| A．each other day | B．every other day | C．each of two days | D．every of two days |