39) How many taps are in one tap set ?

40) In the case of blind hole, which type of tap must be used ?

41) Which type of die stock is called a "quick cut die stock"

42) M4 x 20 is a machine screw of metric thread having 4 mm diameter and length is :

43) M4 x 20 is a machine screw of metric thread of 20 mm length and 4 mm is :