真的猛士，____，敢于正视淋漓的鲜血。（《记念刘和珍君》）

Most parents forbid their children_______ much time ______ TV. They think it's a waste of time.

① 2O₂(g)＋N₂(g)＝N₂O₄(l)  ΔH₁

② N₂(g)＋2H₂(g)＝N₂H₄(l)  ΔH₂

③ O₂(g)＋2H₂(g)＝2H₂O(g)  ΔH₃

④ 2 N₂H₄(l)＋N₂O₄(l)＝3N₂(g)＋4H₂O(g)  ΔH₄=﹣1048.9 kJ·mol^－1