I need help finding out what 7x8 is

Which theme is best supported by the descriptive detail in this passage from my antonia

Which of the following sentences uses dashes correctly? a. i looked under the bed - get this - and there it was! b. i need - a lot of - colors for this painting. c. i can't believe my own - brother! - is now a mayor. d. tom and i - are planning - a wedding in june.

What is one thing that happened to benno harte when he and his family left france to escape the nazis?