在标况下，下列各组气体混合其平均相对分子量可达到40的是

A．N₂和O₂

B．CO₂和O₂

C．SO₂和CO₂

D．HI和HCl

---Why does she always ask you for help?  ---There is no one else ________, is there?

A．who to turn to

B．she can turn to

C．for whom to turn

D．for her to turn