A rotation can be mandatory.Logical formLearned from64 sentences. Savings can be mandatory.Logical formLearned from64 sentences. A break can be mandatory.Logical formLearned from64 sentences. Safety can be mandatory.Logical formLearned from63 sentences. (Waiting periods) can be mandatory.Logical formLearned from63 sentences. A procedure can be mandatory.Logical formLearned from63 sentences. (Pollution reductions) can be mandatory.Logical formLearned from63 sentences. A secondary education can be mandatory.Logical formLearned from62 sentences. Ones can be mandatory.Logical formLearned from62 sentences. A session can be mandatory.Logical formLearned from62 sentences. A kill can be mandatory.Logical formLearned from62 sentences. A membership can be mandatory.Logical formLearned from60 sentences. A sterilization can be mandatory.Logical formLearned from60 sentences. (Class attendance) can be mandatory.Logical formLearned from60 sentences. (Detention laws) can be mandatory.Logical formLearned from60 sentences.