题干
—Where is Lucy? I can't find her now.
—She ___________ Shanghai on business. She ___________ back in three days.
A：has been to; comes
B：has been to; will come
C：has gone to; comes
D：has gone to; will come
答案(点此获取答案解析）
D
2HNO3＋4N2＋9H2O，在反应中被氧化与被还原的氮原子数之比为（ ）
