21.
Engine cranks do no start during winter because of
1. Battery discharge
2. Weak spark
3. Worn out engine
4. Lean mixture

28.
Which one of the following method for determination of engine friction is only applicable for diesel engines and also the gross fuel consumption is plotted against brake power and it is extended backwards to zero fuel consumption?

29.
High performance sports car with active exhaust system allows . . . . . . . .