Weknowthattreesar的精选

问题详情：完形填空，从每小题A、B、C、D四个选项中，选择能填入相应空白处的最佳*。Weknowthattreesareusefulinoureverydaylife.They  1 usmanythings,suchaswood,oxygen(氧气),rubber(橡胶),medicinesandmanyotherthi...