The wider China opens its door to the outside world, the more people find _____important and necessary to study foreign languages.
| A．is | B．them | C．it | D．more |
Their relationship_______ ups and downs over the past century.
| A．will see | B．sees |
| C．has seen | D．had seen |
________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 |