difficult

a.困难的，艰难的；难应付的，难满足的

die-hard, diehard, dieresis, diesel, diesel-electric, diet, dietary, dieter, dietetic, dietetics, dietician (also dietitian), differ, difference, different, differential, differential calculus, differentiate, differentiated, differentiation, differently, difficulty, diffidence, diffident, diffidently, diffract, diffraction, diffuse, diffusely, diffuseness, diffusion, dig, dig down, dig in, dig out, dig up, digest, digestibility, digestible, digestion, digestive,