diffractionn.[物理]衍射;绕射
diffidencen.无自信;内向;羞怯
Diffidenti迪菲登蒂
diffidentlyadv.胆怯地;羞怯地
diffidentnessn.缺乏自信
"she was diffident when offering a comment on the professor's lecture"
"stood in the doorway diffident and abashed""problems that call for bold not timid responses""a very unsure young man"