问题
单项选择题
发动机润滑油腐蚀度测定法所用的金属试片的材质是（）。
A、钢片
B、铝片
C、铁片
D、铜片
答案
参考答案：A
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发动机润滑油腐蚀度测定法所用的金属试片的材质是（）。
A、钢片
B、铝片
C、铁片
D、铜片
参考答案：A
| In most cases, you can transplant a tree successfully, at any time, if you follow the instructions for planting a tree. The most important thing is to dig out enough roots, but this process is difficult with a large tree. When you dig out the tree, leave a ball of earth around its roots. This ball of earth should measure about a foot wide for every inch of the tree trunk’s diameter. Dig deep enough to avoid cutting off too many taproots. It is wise to call in a professional tree expert to transplant a tree more than a few inches in trunk diameter. |
The taproots are ______.
A．the heaviest roots
B．the principal, deepest roots
C．the ball of earth
D．the same width as the trunk’s diameter