Choosing to visit the Shanghai Expo on a late afternoon canmake you see two to three times as many of the most popular pavilions between 6pm and closing time ____ you hurry.

Figures show that 6 to 10 percent of Internet users become _______ and waste a lot of time.

The difference in achievement between the pupils arepartly ________by their differences in age.

Jack wasn’t saying anything，but the teacher smiled at him _______he had done something very clever．[ ]

___ that he had fallen behind,he tried to workharder.