/ SURVIVE / WE / UNLESS / WORK / START / CLEANER / SAFER / ENERGY /...

7. / survive / we / unless / work / start / cleaner / safer / energy / sources / A. We won’t survive so we start working on cleaner,safer sources of energy. B. We won’t survive although we start working on cleaner, safer sources of energy. C. We won’t survive unless we start working on cleaner, safer sources of D. We won’t survive otherwise we start working on cleaner, safer sources of