从A、B、C、D四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
21.-Many people have been ill from a strange disease these days, _______we have never heard of before
A. it B. that C. one D. this
22. He made too many mistakes in the exam. To ______ it another way，he failed to pass the examination.
A．put B．place C．set D．speak
23. After climbing up the top of the mountains, the three of them sat there, _______.
A. hungry and tiredly B. hungrily and tiredly
C. hungry and tired D. hungrily and tired
