题干
There was a time ______ I thought my dad didn't know a thing about being a good father.
A：when
B：which
C：that
D：what
答案(点此获取答案解析）
A
There was a time ______ I thought my dad didn't know a thing about being a good father.
A：when
B：which
C：that
D：what
4CO2+2X+6H2O，则X的化学式为（ ）