问题
选择题
| 由以下数据能估算出水分子直径的是（ ） A．水的质量、水的体积和阿伏加德罗常数 B．水的质量、水的密度和阿伏加德罗常数 C．水的摩尔质量和阿伏加德罗常数 D．水的摩尔体积和阿伏加德罗常数 |
答案
答案：D
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| 由以下数据能估算出水分子直径的是（ ） A．水的质量、水的体积和阿伏加德罗常数 B．水的质量、水的密度和阿伏加德罗常数 C．水的摩尔质量和阿伏加德罗常数 D．水的摩尔体积和阿伏加德罗常数 |
答案：D
| 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