instruction:
Translate the given Spanish text to English
question:
Formula (A-) a .
answer:
Formula (A-)a.


question:
Methods of preparing the copper compositions are also disclosed.
answer:
Tambien se describen metodos para preparar las composiciones de cobre.


question:
Variables Ring A, Ring B, Ring C, X1, X6, and X8 are as defined herein.
answer:

Las variables Anillo A, Anillo B, Anillo C, X1, X6 y X8 son como se definen en la presente.