White smoke exhausting from a diesel engine can be caused by a （）

A.low combustion temperature
B.a leaking fuel nozzle check valve
C.late fuel injection
D.plugged oil-scraper ring hole

A.the engine is overloaded
B.the engine is cold
C.there is too much lube oil in the cylinders
D.the turbocharger is fouled

A.high exhaust temperature
B.high lube oil temperature
C.low turbo-charger speed
D.low cooling water temperature