题干
—Hurry up. The bus is coming.
—Wait a minute. Don't cross the street _______ the traffic lights are green.
A：after
B：until
C：while
D：since
答案(点此获取答案解析）
B
—Hurry up. The bus is coming.
—Wait a minute. Don't cross the street _______ the traffic lights are green.
A：after
B：until
C：while
D：since
2HNO3＋NO ΔH<0，为提高NO2的转化率，理论上应该采取的措施是（ ）