The poem 'Harlem' is an example of free verse. The meter is irregular and there is also an irregular rhyme scheme (2nd line rhyme with 4th, 5th with 7th and 9th with 10th)
D) The discovery that the Universe is expanding was the greatest discovery of the century.
The usage of at is the error
Explanation:
IN is for large spaces that can enclose (village, city, state, province, country, continent, mountain range, desert, zone, etc.)
ON is for surfaces.( street/avenue/road, most bodies of water, etc)
AT is for points ( We live at an address, at a certain point and at a certain person’s residence if just the possessive case is used to mean the residence.)
Examples:
1- I live in Belgrade.
2-They live on Mulberry Street
3-I live at 199 Main Street
Conclusion: AT is a tiny point, ON is bigger, and IN is big enough to surround you.
