When working with additional information in a sentence, when should dashes be used instead of commas or parentheses?

Which detail from the text best demonstrates the effect of totalitarianism on the animals? "progress was made in the dry frosty weather that followed." "it had been decided to build the walls three feet thick." "they were always cold, and usually hungry as well." "for a long time the quarry was full of snowdrifts and nothing could be done."

In the por "heaven" what things does echo say will last?

Yosemite has spectacular scenery and which has half-time bears. how do i write i. parallel structure?