--Have you got a digital camera?---No.---You should buy________.
22.After playing in the park for a few hours, the pupils gathered under trees _______shade and ________ down to eat their picnic lunch.
21.It was not until dark ____ he found ____ he thought was the correct way to slove the problem.
20.—Though it is 30 years _____ we last met, I still remember the scene _____ we got separated on a rainy day.
19.—My cat’s really fat. —You ______ have given her so much food.
18.—Jim, are you ______ this Saturday?—Oh, sorry. I need to go to the bookshop _____ the bank on Saturday.