化简-b•b3•(-b)4的正确结果是( )
A:-b8
B:b7
C:-b7
D:b8
防火、灭火、自救等安全知识是每个人都应该了解的生活常识.下列做法错误的是( )
My friends thought they had made things very smooth for me, but I felt there was still much to ________ with.