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£¨¡¡£©21£®The woods and the newly-dug river through the campus       the beauty of this world-known university.

¡¡¡¡¡¡¡¡A£®add up         B£®add to                 C£®are added up        D£®are added to

£¨¡¡£©22£®In order to make our city green,        .

¡¡¡¡¡¡¡¡A£®it is necessary to have planted more trees   B£®our city needs more trees

C£®many more trees need to plant        D£®we must plant more trees