When I cut the onions, I teared up.
You must be a genius if you could make this onion stand up by itself.
How many onions can you hold under your armpits?
ねぎ means "onion" in Japanese. But, there are different kinds of onions, right? This happens to be a "ball onion," which is just one of those round ones, like a Walla Walla Sweet Onion. Do you know?
Since this word consists of a kanji with hiragana attached, you can guess it will probably use the kun'yomi reading. Luckily, that's the reading you learned with the only kanji in this word, so you should be able to read it!