—Would you like to go for an outing with us?
— , for I have something important to do.
| A．I will | B．I'd love to | C．I don't know | D．I'd rather not |
________carefully if any change occurs when doing experiments in the lab.
| A．Observe | B．To observe |
| C．Observed | D．Observing |
______ before bed, cellphones can result in a restless night.
| A．To use | B．Using | C．Used | D．Having used |
Love is_____ makes you smile when you are tired.
| A．that | B．what | C．it | D．which |
How can you imagine the difficulty I had______ to the school life?
| A．to adapt | B．adapt | C．adapting | D．adapted |
The Romany are thought _______ from India.
| A．to have come | B．to come |
| C．to coming | D．to be coming |