The plural of ox does NOT follow the usual rules for making a plural word.
More than 1 ox is oxen, usually meaning a pair of 2.
The farmer's team of oxen plowed the field.
Oxes is not a word in the English language.
Yes it is spelled correctly
You have spelled 'still' correctly.
Yes, engineer is spelled correctly in your question.
Flattest is spelled correctly. The others are spelled: silliest, biggest and sweetest.
Yes, surprisingly is spelled with an S. Surprisingly is how you spell it. You spelled it correctly.
You've spelled it correctly.
Convenience (easy access or availability) is correctly spelled.
It should be foreign.
yes, that is correct.
No, "infrachrondal" is not spelled correctly. The correct spelling is "infrachondral."
Correctly: How did Elise spell? She spelled correctly.
it is correctly spelled iPod.