21. I will make _____ deal with you—you wash the car and I’ll let you use it free of ____ charge.
A. a, a B. 不填，a C. a, 不填 D. a, the
22. The beautiful city Qingdao, _____ on the east coast of China, attracts a lot of tourists every year.
A. situated B. spotting C. locating D. lain
23. It was not until the boat was out of sight ______ their hands.
A. did they stop waving B. that they stopped waving
C. they didn’t stop waving D. had they stopped waving
