21. The boy sat there sad, _______ by his friends.
A. feeling betrayed B. to be betrayed C. been betrayed D. having betrayed
22.The girl is _______ to give us some help if asked.
A. possible B. likely C. probably D. possibly
23.The people are ______ about the newly-made discoveries ______ the change of people’s way of life in the future.
A. concerned; concerned B. concerning; concerning
C. concerning; concerned D. concerned; concerning
