Why would a poet vary the number of feet in lines of poetry?

What symbolic aspect did brother vu and mother leave behind? book = inside out and back again

Fine fellow, that lebrun," said arobin when robert had gone. "i never heard you speak of him.""i knew him last summer at grand isle," she replied.  what becomes apparent during this conversation? robert and arobin are both aware they are rivals for edna’s affections.arobin is unaware of robert’s role in edna’s life, but robert is aware of arobin’s role.robert is completely unaware of arobin’s romantic intentions and love for edna.robert has much more confidence in himself than arobin does.

In mandatory military service in america one of the main arguments states that americans should share benefits and responsibilities of citizenship.