整式A与m2+2mn+n2的和是(m﹣n)2,则A=____ .
the kind driver, the old man was saved by the doctors.
世界最高峰珠穆朗玛峰海拔8848.13米,我国吐鲁番盆地最低处海拔-155米,两地之间的相对高度是
—________________.