如图,△ABC中,∠ACB=900,AC=6,BC=8,D是AB的中点,CE⊥AB于E,则CD= ▲ ,CE= ▲ .
计算: (1)-0.10=________;(2)(-0.1)0=_______; (3)(-0.5)-2=_______; (4)(-)-1=________.
a0=______(a≠0);a-p=_______(a≠0,p是正整数).
代数式的意义为___________.
计算: (1)199.92=_______;(2)512=________;(3)1-2×51+512=_______.
计算:-3a×(-3a)=________.