时值深秋，一行大雁打光秃秃的椿树头顶掠过，惊动了三三两两浮在梧桐枝头的乌鸦。
O O B-Time I-Time O B-Metric I-Metric B-Thing I-Thing O O O O O B-Location I-Location I-Location I-Location O O O O O O B-Metric I-Metric I-Metric I-Metric O O B-Location I-Location I-Location I-Location O B-Thing I-Thing O