The primary cause of civil aviation accident in nowadays is（ ）
举一反三
- The civil aviation accident is likely to happen at which phase? （ ）
- CAAC refers to Civil Aviation Administration of ( )
- The Civil Aviation Administration of China announced that nobody on the plane was hurt.
- China's civil aviation began to develop rapidly in the 1990s.
- —————————— is not clear. A: what caused the accident B: what did cause the accident