Using Dash

Insert dashes where needed, if needed.
The only thing Felix could do if he could do anything was to sit and wait for the results

• The only thing Felix could do if he could do anything--was to sit and wait for the results.
• The only thing Felix could do if he could do anything was to sit and wait for the results.
• The only thing Felix could do--if he could do anything--was to sit and wait for the results
• The only thing--Felix--could do if he could do anything was to sit and wait for the results.

Which sentence has the dash in the correct place?

• Our agents--were undertaking a special mission in Reims a mission that Delphine had spearheaded under my direction.

• Our agents were undertaking a special mission in--Reims a mission that Delphine had spearheaded under my direction.

• Our agents were undertaking a special mission in Reims--a mission that Delphine had spearheaded under my direction.

• Our agents were undertaking a special mission in Reims a mission that Delphine had spearheaded--under my direction.

Which sentence uses dashes correctly?

• If I knew everything -- which I don't -- then my grade would be much higher.

• If I knew everything which I don't then -- my grade would be much higher.

Place a dash after:  It’s not only our lives on the line it’s the lives of thousands of Allied soldiers.

• NOT
• ONLY
• LINE
• ALLIED

Which is the correct way to use the dash in the following:

The Beatles the most famous rock band in history were from England.

• The Beatles, the most famous rock band in history -- were from England.

• The Beatles -- the most famous rock band in history -- were from England.

• The Beatles -- the most famous rock band in history; were from England.

• The Beatles--the most famous rock band in history were from England.