n.自动阀，自动活门，阀式放电器...

oval的复数形式为：ovals...

In covalent bonding, atoms share electrons.在共价键联中, 原子共有电子.Crystals may be classified as either ionic or covalent by analogy with molecules.与分子的情况一样,晶体也可以分为离子键型和共价键型.Ceramics primarily have ionic bonds, but covalent bondi...

adj.电价的...