题目

As a teacher, my daily activity involves driving to a new school almost every day. On one particular day, I was teaching in a very   20 classroom. I was managing behavior all morning, and by lunchtime I knew I needed a coffee to     21 the afternoon. So during my lunch break, I drove to a nearby square to get a coffee. Upon returning to the     22 , I realized I had locked my phone and my     23 inside! I had about 15 minutes to get back to the     24 , which was a good five-minute drive. If I ran back really quickly, I could    25 it. But it was winter, and a sud双子叶植物和单子叶植物的根本差别在于（    ） A．子叶数目不同                      B．是否有胚乳 C．胚芽的数目不同                    D．胚的数目不同