7.70.3 Can you answer these questions?

7.70.3.1 new command within table parameters

https://tex.stackexchange.com/landing/r/digest?cta=question&id=621654

I used \newcommand to define a variable and I used that variable in one of the table parameters but that produced an error 
Here is my code: 
\documentclass[a4paper,11pt,english]{report} 
\usepackage{... 
[tables] [macros] [environments] [longtable]
 

asked by Nour https://tex.stackexchange.com/landing/r/digest?cta=user&id=252400 1 vote

7.70.3.2 Duplicate entries in contents

https://tex.stackexchange.com/landing/r/digest?cta=question&id=621194

I found a lot of questions with the same problem.But mine is a little different. 
\documentclass{report} 
\usepackage{titlesec} 
\begin{document} 
\tableofcontents 
\pagebreak 
\setcounter{chapter}{2} 
\... 
[table-of-contents] [books]
 

asked by A Y https://tex.stackexchange.com/landing/r/digest?cta=user&id=251249 1 vote

answered by A Y https://tex.stackexchange.com/landing/r/digest?cta=user&id=251249 0 votes

7.70.3.3 Global table formatting, thin and think hlines, apply to all tables

https://tex.stackexchange.com/landing/r/digest?cta=question&id=621071

How can I define a table formatting style that will automatically be used throughout my document? For example, I understand that I can use the caption package to specify caption formatting used ... 
[tables] [formatting]
 

asked by a11 https://tex.stackexchange.com/landing/r/digest?cta=user&id=246855 1 vote