Step-by-step explanation:
A) I choose the poem of "Dust and Snow" which expresses emotions and how they change suddenly. Poet - Robert Frost.
"The way a crow,
shook down on me
The dust of snow
From a hemlock tree
Has given my heart,
a change of mood
and saved some part
of the day I rued"
-- Robert Frost
B) The poem says that the poet's day was about to be ruined as his day started with miseries. But when the crow accidentally shook some snow from a hemlock tree, saved the day that he was going to waste. We need to note that "hemlock tree" , "crow" , "dust" all are considered to be bad. But in this poem, it shows us that it can even make a person happy.
Hope it helps :)