Three seeding groups of Acer negundo L.were treated with simulated acid rain at pH 3 .0, 4.5 and 5 .6 levels for three months.是什么意思_Three seeding groups of Acer negundo L.were treated with simulated acid rain at pH 3 .0, 4.5 and 5 .6 levels for three months.在线翻译_英语_读音_用法_例句