A、△H<sub>1sub>+ △H<sub>2sub>+△H<sub>3sub> =△H<sub>4sub> B、△H<sub>1sub>+ △H<sub>2sub> = △H<sub>3sub> +△H<sub>4sub> C、(△H<sub>1sub>+ △H<sub>2sub>)-(△H<sub>3sub> +△H<sub>4sub>)=△H<sub>5sub> D、△H<sub>1sub>+△H<sub>2sub>+△H<sub>3sub>+△H<sub>4sub> =△H<sub>5sub>