| Trees should only be pruned (修剪) when
there is a good reason for doing so. Many gardeners believe that more damage
results from doing it unnecessarily than from leaving the tree to grow in its
own way. First, pruning may be done to make sure that trees have a desired shape. The object may be to get a tree of the right height, and to help the growth of small side branches which will thicken its appearance or give it a special shape. Secondly, pruning may be done to make the tree healthier. You may cut out diseased or dead wood, or branches that are rubbing against each other and thus causing wounds. A tree may grow healthier by removing the branches that are locking up the centre and so preventing the free movement of air. One result of pruning is that an open wound is left on the tree and this provides an easy entry (进入) f A. the cut surface can heal more quickly B. open wounds on the tree run the less risk of getting diseased C. a gardener can do pruning more easily D. the leaves can interfere [判断题]气瓶搬运应使用专门的抬架或手推车。
A.正确 B.错误 [单选题]判断下列有关化学基本概念的依据正确的是()
A.以聚丙烯为原料制造的“熔喷布”可用于医疗、环保等领域,聚丙烯属于纯净物 B.共价化合物:是否含有共价键 C.强、弱电解质:溶液的导电能力大小 D.氧化还原反应:元素化合价是否变化 [单项选择]在管道平面的布置图中，有两条交叉管线，断开的一条管线在（）
A. 左面 B. 右面 C. 上面 D. 下面 [多选题]《中国铁路上海局集团有限公司高速铁路行车组织细则》（上铁师〔2018〕15号）规定，车站负责吸污作业的组织，根据列车运行图制定的吸污计划，将吸污列车的( )通知吸污作业单位。
A.车次 B.停靠股道 C.到发时刻 D.编组 [多项选择]下列关于民间非营利组织会计核算的表述中，不正确的有（）。
A. 民间非营利组织在确认收入时，应当遵照收付实现制原则 B. 对于民间非营利组织受赠的非现金资产，如果捐赠方未提供有关凭据的，应按名义金额1元入账 C. 捐赠承诺不满足非交换交易收入的确认条件 D. 民间非营利组织的会费收^、一般为非限定性收入 [多选题]20/5t起重机电气控制线路中主钩电动机由( )来实现控制。
A.凸轮控制器 B.主令控制器 C.交流保护控制柜 D.磁力控制屏 E.主钩制动电磁铁 我来回答: 提交
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