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A lot of trees _________ around here every year, and we can enjoy fresher air now.
We were dying to hear the announcement of the winner of the race.
如图所示,实线和虚线分别表示振幅、频率均相同的两列波的波峰和波谷.此刻,M是波峰与波峰相遇点,下列说法中正确的是( )