---Will you be back ____ five in the afternoon?

　---I’m not sure, maybe later than that.

A．in　

B．before　

C．for　

D．until

下列各组热化学方程式中，△H₁>△H₂的是

①C(s)＋O₂(g)===CO₂(g)  △H₁           C(s)＋1/2O₂(g)="==CO" (g) △H₂

②S(s)＋O₂(g)===SO₂(g)  △H₁           S(g)＋O₂(g)===SO₂ (g)  △H₂

③H₂(g)＋1/2O₂(g)===H₂O(l) △H₁        2H₂(g)＋O₂(g)===2H₂O (l) △H₂

④CaCO₃(s)===CaO(s)＋CO₂(g) △H₁      CaO(s)＋H₂O(l)===Ca(OH)₂ (s) △H₂

A．①

B．②③④

C．④

D．①②