I can't believe it I only 如果 B项改为 had worked 那对 意思是 在 获得B之前

I can't believe it I only 如果 B项改为 had worked 那对 意思是 在 获得B之前 已经学习了几个周－I can’t believe it!I only got a B on my project.－That’s not a bad grade.－But I on it for weeks.A.am working B.have worked C.work D.worked