difficultness
词形变化：
副词: difficultly |
同义词：
hard | rough | rugged | arduous | complicated | trying | tough | incomprehensible | laborious | puzzling | wicked | painful | ornery | troublesome | sticky | wretched | wayward | fussy | strenuous | stiff | formidable | exacting | tricky | thorny | problematic | grim | abstract | unintelligible | abstruse | impenetrable | involved | obstinate | stubborn | recalcitrant | intractable | unmanageable |
反义词：