It is acceptable to manage all the possible conflicts in a friendly ____ (方式).
a、b两个电阻的U—I图线如图所示,则( )
(1)下列代数式哪些书写不规范,请改正过来.
①3x+1;②m×n﹣3;③2×y;④am+bn元;⑤a÷(b+c);⑥a﹣1÷b
(2)说出下列代数式的意义:
①2(a+3);②a2+b2;③n+1n-a.