A:I’m not invited
B:I was not invited
C:I have not been invited
D:I had not been invited
①质量和体积适中 ②与恒星的距离比较适中
③处于比较安全的宇宙环境之中④昼夜更替的周期较适中
“知人者智,自知者明。”说明了( )