成绩退步 (grades fall behind)成绩下滑 (grades decline)成绩不佳 (poor grades)成绩不如预期 (grades lower than expected)成绩不及格 (fail grades)学业不振 (academic decline)学习情况欠佳 (poor academic performance)学习成绩下降 (decline in academic performance)没有取得好成绩 (not achieving good grades)学习成绩不理想 (unsatisfactory academic performance)