A successful scientist needs _____ if he wants to make hypothesis (假设) of how processes work and how events take place.
“Drive-ins” have large parking lots ________ customers are served in their cars by waitresses.
We rushed to the football court, only to see a sign ________ into the ground reading PERIODIC MAINTENANCE (定期维修).
The Japanese people keep up cheerful spirits ________ the world that they can get over the crisis caused by the terrible tsunami(海啸).
The government spokesman has to ________ his words before responding to reporters.
Due to a terrible flu that ________ on, many students don’t show up to school today.