Uncle Vernon ripped open the bill, snorted in disgust, and flipped over the postcard . " Marge's ill, " he informed Aunt Petunia. " Ate a funny whelk. --."
If you're studying for a chemistry exam, one card can ask you what the chemical symbol for Neon is, and if you flip it over, it can also make sure you know what Ne represents.
如果你正准备化学考试,张卡片可以考查你氖化学符号是什么,把它翻转来,它也可以确保你知道 Ne 代表是什么。