______ carefully if any change occurs when doing experiments in the lab.
| A．Observe |
| B．To observe |
| C．Observed |
| D．Observing |
—Has James arrived at the hotel?
—No, he ______ by fans for photographs at the airport.
| A．has surrounded |
| B．would surround |
| C．was surrounded |
| D．is being surrounded |
______ she has earned her PhD, she wants to find a job with higher pay.
| A．As if | B．Now that |
| C．Even though | D．In case |
Prince William took a visit to the Forbidden City on Feb. 28, ______ emperors once lived.
| A．which | B．whose | C．where | D．when |
Mike will become the first person in his family ______ college education.
| A．finished |
| B．having finished |
| C．finishing |
| D．to finish |
The long lasting cold current has brought ________ winter in my memory to the east coast of the United States.
| A．the longer | B．the longest |
| C．a longer | D．a long |