问题:
(1)1×(-5)=______,(-1)×(-5)=______,+(-5)=______,-(-5)=______;
(2)1×a=______,(-1)×a=______.
(1)1×(-5)=______,(-1)×(-5)=______,+(-5)=______,-(-5)=______;
(2)1×a=______,(-1)×a=______.
(2)1×a=______,(-1)×a=______.
参考答案: