A C is true
B C is false
C C is unknown
D A is false
Explanation: A∧C→B and B is false means A∧C is false. Since A is true, C must be false.
A All organic fruits are healthy
B Some organic fruits may be healthy
C No organic fruits are healthy
D All healthy foods are organic
Explanation: We can only conclude that some organic fruits may be healthy.
A Green buildings use efficient materials
B Efficiency saves energy
C Energy savings are valuable
D All of the above
Explanation: For the argument to hold, all these assumptions must be true.
A Contradiction
B B is true
C B is false
D A is false
Explanation: A↔B and A true means B true. B↔C and B true means C true. But C is false, creating a contradiction.
A All students are reliable
B Some students may be reliable
C No students are reliable
D All reliable people are scientists
Explanation: We can only conclude that some students may be reliable scientists.
A Education is valuable
B Graduates may come from wealthier backgrounds
C Income indicates success
D College is accessible
Explanation: If graduates come from wealthier backgrounds, their higher income may not be due to education.
A P is true
B P is false
C Q is false
D R is false
Explanation: Q∧R→S and S is false means Q∧R is false. But Q and R are both true, so contradiction. This means the premise P→Q and P→R combined with Q and R being true but S false implies P must be false.
A All reference books are verified
B Some reference books may contain verified facts
C No reference books are verified
D All verified facts are in reference books
Explanation: We can only conclude that some reference books may contain verified facts.
A Cars need maintenance
B Fewer problems indicate prevention
C Maintenance is affordable
D Cars are important
Explanation: If fewer problems indicate prevention, this strengthens the maintenance-breakdown link.
A B is true
B C is true
C D is true
D All of B-D are false
Explanation: By modus tollens backwards, E false means D false, C false, B false.
A All海洋 creatures are bioluminescent
B Some海洋 creatures may be bioluminescent
C No海洋 creatures are bioluminescent
D All bioluminescent things are海洋 creatures
Explanation: We can only conclude that some海洋 creatures may be bioluminescent.
A Mentoring provides guidance
B Guidance helps careers
C Networks are valuable
D All of the above
Explanation: For the argument to hold, all these assumptions must be true.
A A is true
B B is true
C C is true
D A, B, C are all false
Explanation: If D is true and only one is true, A, B, C must all be false.
A All countries need foreign investment
B Some developing countries may benefit from foreign investment
C No countries need foreign investment
D All foreign investment goes to developing countries
Explanation: We can only conclude that some developing countries may benefit from foreign investment.
A Companies hire based on demand
B Tax breaks may increase profits without hiring
C Job creation is good
D Businesses need money
Explanation: If tax breaks increase profits without hiring, the job creation claim is weakened.
A C is true
B C is false
C C is unknown
D A or B is false
Explanation: A∧B→C and both A and B are true means C must be true.
A All students get published
B Some students may get published
C No students get published
D All published people are students
Explanation: We can only conclude that some students may get published.
A Bilingual education is popular
B Cognitive tests measure cognitive abilities
C Cognitive abilities are important
D Tests are standardized
Explanation: If cognitive tests measure cognitive abilities, higher scores strengthen the bilingual-cognition link.
A Q is true
B R is true
C S is true
D All of Q-S are false
Explanation: By modus tollens backwards, T false means S false, R false, Q false.
A All进口的fruits create emissions
B Some进口的fruits may create emissions
C No进口的fruits create emissions
D All emissions come from fruits
Explanation: All进口的fruits are transported, transportation requires fuel, and fuel creates emissions, so all进口的fruits create emissions.