You are required _________ all the food you take in this buffet (自助餐) restaurant.

Currently it is difficult to find a good job in thefierce job-hunting market —_____ But highly-qualified graduatesare always in great demand

I want to buy the book Harry Potter. Do youknow its _______ — Not very well. Maybe fifty yuan.

When you leave, please turn off the light _____energy（能源）.

MrSmith would have come to see you if it had been possible, but he __________ so busy