The words "pleasant morn" help the reader understand before the arrival of the troops.

"Barbara Frietchie" is a narrative poem written by Whittier in a setting of Civil war that was taking place then. It is a rhythmic poem written in ballads, i.e, couplets.

Explanation:

This poem is completely based on a background of Civil war where there are soldiers marching, troops are getting ready for the fight, civilians are waiting for a better day to start and how the weather conditions are, at the time of the war.

The poet talks about the nature being the same though people have been fighting in a war against each other. When he writes about the hills and the orchids, he is trying to talk about the environment that suffered too but bloomed back with a hope that everything shall be alright later. With starving comrades - famished rebels, still we look forward to fight for our nation.

Though it is a pleasant morning, there will be war and there will be bloodshed - is what the setting explains.

Explanation:

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).