买一个书包66元,妈妈给了售货员阿姨100元钱,应找回多少?
100-66=34(元)
多项式m2﹣4n2与m2﹣4mn+4n2的公因式是( )
食物链的起始环节是消费者.
—I don't know. It ____ (mend) by my brother now.