My English ability in all four skills are steadily improving.
My English ability in all four skills are showing steady signs of improvement.
"My English ability in all four skills are definitely improving.":
"My English ability"=「私の英語能力」
"in all four skills"＝「四技能全て」
"are steadily improving"＝「は着実に良くなっている」
"showing steady signs of improvement"＝「順調な進歩のサインを見せている」
アメリカ合衆国 
