According to the Chinese standard, vehicle axles are classified into seven types, the type-1 and type-2 axles are the single axles, type-3,type-4, and type-5 are the ______ axles, while type-6 and type-7 are the ______axles. A: Tandem; Tridem B: Single; Tridem C: Tandem; Single D: Tandem; Tandem

According to the Chinese standard, vehicle axles are classified into seven types, the type-1 and type-2 axles are the single axles, type-3,type-4, and type-5 are the ______  axles, while type-6 and type-7 are the ______axles. A: Tandem; Tridem B: Single; Tridem C: Tandem; Single D: Tandem; Tandem