Shells may crash.Logical formLearned from21 sentences. Aircraft may crash.Logical formLearned from21 sentences. Terrorists may crash airplanes.Logical formLearned from20 sentences. A civilian helicopter may crash.Logical formLearned from20 sentences. A day may crash.Logical formLearned from20 sentences. Stock may crash.Logical formLearned from20 sentences. Trains may crash.Logical formLearned from20 sentences. A copter may crash.Logical formLearned from20 sentences. A deity may crash.Logical formLearned from20 sentences. (Firefighting plane) may crash.Logical formLearned from20 sentences. A (passenger plane) may crash after takeoff.Logical formLearned from20 sentences. A mood may crash.Logical formLearned from20 sentences. A helicopter may crash in waters.Logical formLearned from20 sentences. Some planes may crash in a US-city.Logical formLearned from20 sentences. Financial markets may crash.Logical formLearned from20 sentences.