It was last night ________ I see the comet.( ) A. the time B. when C. that D. which 答案:C 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.④
C.②③④
D.①②③