空间对称的极性键分布，还是会导致整个分子为非极性分子。
Symmetric disposition of polar bonds still results in a nonpolar molecule.
第二种构成，需要空间非极性，就是需要极性键的空间对称分布。
The second way to have something that is net nonpolar is to have spatially symmetric disposition of polar bonds.
第二种构成，需要空间非极性，就是需要极性键的空间对称分布。
The second way to have something that is net nonpolar is to have spatially symmetric disposition of polar bonds.
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