Question

decide whether each sentence is punctuated correctly. use the drop-down if necessary.
when you go to the supermarket, please buy eggs, milk, pears, and carrots
no revision needed
i plan to go skiing with my sisters, charles and boris.
mariana hopes to study chemistry geometry, and italian.
add a comma after chemistry
remove comma after geometry
no revision needed

Explanation:

1. The first sentence uses a comma correctly after the introductory dependent clause, and the Oxford comma in the list is standard and correct.
2. The second sentence incorrectly uses a comma before "Charles and Boris"—since these are not sisters (they are male names), they specify which sisters (likely a joke/error, but grammatically, the comma implies non-restrictive, which is wrong here; the comma should be removed to show restrictive apposition, or rephrased, but the fix is removing the comma).
3. The third sentence is missing a comma in the list between "chemistry" and "geometry" to properly separate the items in the series.

Answer:

1. no revision needed
2. remove comma after sisters
3. add a comma after chemistry