Lead in compounds has valence 2 and 4;an oxide (litharge) is the most widely used. 铅化物的原子价有+2和+4价，其中铅氧化物（密陀僧）是最广为使用的。
It puts forward the importance of verb valence in learning the second language. 并指出了动词配价理论在第二语言学习中的重要性。
I do not claim to know much more about novels than the writing of them, but I cannot imagine one set in the breathing world which lacks any moral valence. 我从不敢声称我对小说的了解远远超过我所写的小说本身，但我不能想象一个人活在这个世界上可以不需要任何精神上的依托。
