单项选择题 Cylinder liners from older lower powered engines had a uniform wall thickness and the cooling was achieved by circulating cooling water through a space formed between （）.

单项选择题 Because of the resulting higher pressures in the cylinder from the combustion of this greater mass of fuel, and the larger diameters, the liner must be made （） at the top to accommodate the higher stresses, and prevent cracking of the material.

单项选择题 Oil is supplied to the crosshead using a swinging arm or a （） and is sometimes boosted in pressure to and efficient lubrication.