装配式混凝土简支梁
prefabricated concrete simply supported beam
四次多项式拟合
4th degree polynomial fit
四分之三浮动式轴
three-quarter floating [rear]axle
四分之一吋匣式磁带
quarter inch cartridge tape
四缸对置式电机驱动往复压缩机
four-cornered motor-driven reciprocating compressor
四缸三胀式发动机
four-cylinder triple-expansion engine
四缸三胀式蒸汽机
four-cylinder triple-expansion engine