________our earth，or else it will be no longer fit for us to live on.
| A．Protecte | B．To protect | C．Protecting | D．Protect |
In the near future, more advances in the robot technology _______ by scientists.
| A．are making | B．are made | C．will make | D．will be made |
Our parents always tell us to believes in we do if we want to succeed.
| A．why | B．how | C．what | D．which |
The doctor advised Lisa strongly that she should take a holiday but _______ didn’t help.
| A．it | B．which | C．what | D．this |
Miss. Gao _______ in the library for three years. But now she is a teacher.
| A．worked | B．has worked | C．had worked | D．has been working |
I'm sorry you've been waiting so long, but it'll still be some time _______ Sundance gets back.
| A．until | B．before | C．after | D．since |