北京的四月，桃红柳绿，扬花点点，似花非花，多少文人墨客对四月赞叹不已，“你是一树一树的花开，是燕在梁间呢喃。
B-Location I-Location O B-Time I-Time O B-Thing O B-Thing O O B-Thing I-Thing O O O O B-Thing I-Thing I-Thing O O O B-Person I-Person I-Person I-Person O B-Thing I-Thing O O O O O O B-Thing O O O O O O B-Thing O O O B-Thing O B-Location I-Location O O O