(Pollution problems) may pertain-to a nation.Logical formLearned from11 sentences. (Air pollution) may undergo a buildup.Logical formLearned from11 sentences. Problems can be with (air pollution).Logical formLearned from11 sentences. Pollution may have an impact.Logical formLearned from11 sentences. A goal can be for curbing pollution.Logical formLearned from11 sentences. Pollution may cause a (greenhouse effect).Logical formLearned from11 sentences. Victims may pertain-to pollution.Logical formLearned from11 sentences. Progress can be against pollution.Logical formLearned from11 sentences. Enterprises may cause pollution.Logical formLearned from10 sentences. (Pollution incidents) can be serious.Logical formLearned from10 sentences. (Pollution control) can be in some (river valleys).Logical formLearned from10 sentences. (Pollution control) may see some positive results.Logical formLearned from10 sentences. Pollution may be caused by ships.Logical formLearned from10 sentences. (Air pollution) may be reported in some cities.Logical formLearned from10 sentences. (Pollution accidents) can be serious.Logical formLearned from10 sentences.