标准状况下的2mol二氧化碳的叙述中，正确的是

A．体积约为22．4 L

B．有4mol原子

C．分子数为6.02×10²³

D．摩尔质量为44g/mol

___ he was ill, I was expected to take his place greatly surprised me for I didn't have much working experience.

A．If

B．That if

C．That

D．If that