5.61×9.9×0.38÷(0.19×3又3/10×1.1)3又3/4×2.84÷3又3/5÷(1又1/2×1.42)×1又4/51998÷1998又1998/1999﹢1/20001/9×(3.47÷5/18-3.6+7.53×3又3/5)1又4/19×(18又2/3-3/4)+20又1/12÷19/23