题干
—I’m sorry I went out for a smoke. I was very tired.
—There’s no ______ for this while you are at work.
—There’s no ______ for this while you are at work.
A：cause
B：excuse
C：matter
D：choice
答案(点此获取答案解析）
B
KCl＋3Cl2↑＋3H2O的反应中，被氧化的氯原子与被还原的氯原子的原子个数比是（ ）