1.21. —Can I look at the menu for a few more minutes before I decide?
—Of course. _______ sir.
(A) Make yourself at home
(B) Enjoy yourself
(C) It doesn't matter
(D) Take your time
2.22. When flint _______ to the market, these products enjoyed great success.
(D) being introduced
3.23. There were dirty marks on her trousers ______ she had wiped her hands.
4.24. The evening news comes on at Seven o' clock and ______ only thirty minutes.
5.25.— Has Sam finished his homework today?
—I have no idea. He ______ it this morning.
(B) has done
(C) was doing
(D) had done