21. Lily was in ____ disturbed state of mind. How could she keep what you said in ____ mind?
A. /; the B. a; / C. the; the D. /; /
22. It was not until I got home _____ that I had left my keys in the office.
A. before I found B. when I found C. did I found D. that I found
23. —What if our demand for more free time to learn by ourselves is not _________ by the school authority?
—Hold on to it until we succeed.
A. approved B. arranged C. applied D. assisted
