1. If national elections deteriorate into TV popularity contests, then smooth-talking morons will get elected. Therefore, if national elections do not deteriorate into TV popularity contests, then smooth-talking morons will not get elected. (N, S)

2. Brazil has a huge foreign debt. Therefore, either Brazil or Argentina has a huge foreign debt. (B, A)

3. If fossil-fuel combustion continues at its present rate, then a greenhouse effect will occur. If a greenhouse effect occurs, then world temperatures will rise. Therefore, if fossil-fuel combustion continues at its present rate, then world temperatures will rise. (F, G, W)

4. If there are dried-up riverbeds on Mars, then water once flowed on the Martian surface. There are dried-up riverbeds on Mars. Therefore, water once flowed on the Martian surface. (D, W)

5. If high school graduates are deficient in reading, they will not be able to compete in the modern world. If high school graduates are deficient in writing, they will not be able to compete in the modern world. Therefore, if high school graduates are deficient in reading, then they are deficient in writing. (R, C, W)

Translate the following arguments into symbolic form. Then determine whether each is valid or invalid by constructing a truth table for each. The letters to be used in constructing the truth tables are given in parentheses.