The carbon deposits on the piston crown and in the ring grooves （）.

Cast iron carrier rings， （） machined grooves， are provided for all the pistons.

The connecting rod large end bearing shell generally has tags for location and oil grooves round the center of its axial length which correspond with grooves in the （） through which oil is transmitted up the rod to lubricate the small end.

The bearing shell generally has （） for location and oil grooves round the center of its axial length.

Which of the following features are machined technical features? A: Bosses B: Chamfers C: Relief grooves D: Casting corners E: Tool recesses

Which of the following manifestations indicates early stage of rickets? () A: Harrison grooves and ribs valgus B: squared skull C: low spirits D: sweating, easily irritated E: convulsions or tetany

Why does the surface of the brain contain folds？（ ） A: They look stylish B: Pressure from cerebral fluids C: To match the grooves on the inside of the skull D: They allow for more brain tissue to fit in the skull