21．——Did you see Lucy last night ?She must have left home as she was wondering round the town at midnight .
——The fact that she was wondering round the town at midnight
she had left home for good .
A. was not meaning B. does not mean
C. was not mean D. would not mean
22．By the time Californiato become the 31th federal state of the USA in 1850, it was already a multicultural society.
A. selected B. collected C. existed D. elected
23．It happens in plants when gardeners take cuttings from growing plants to make new.
A. ones B. one C. others D. other ones