题干
Mr. Xie wants to know _________ for school this morning.
A：why were you late
B：why are you late
C：why you were late
D：why you are late
答案(点此获取答案解析）
C
A：why were you late
B：why are you late
C：why you were late
D：why you are late
H2（g）+CO2（g） 
H>0