下列从左到右的变形哪个是分解因式( )
A:x2+2x=xx+2
B:ma+mb+na+nb=ma+b+n
C:x2-12x+36=xx-12+36
D:-2mm+n=-2m2-2mn
写出字的笔顺。
四:____ ____ ____ ____ ____
Scientists say it may be a few years ______ it is possible to test the new medicine on patients.
我国封建社会形成于春秋时期。____