doubtful

a.怀疑的，可疑的；难料的

double-check, double-cross, double-dealer, double-dealing, double-decker, double-dyed, double-edged, double-faced, double-glaze, double-glazing, double-jointed, double-park, double-quick, double-stop, double-talk, double-think, doublet, doubly, doubt, doubter, doubtfully, doubting Thomas, doubtless, douche, dough, doughnut, doughty, doughy, dour, dourly, douse, douse (also dowse), dove, dovecote, Dover, dovetail, dowager, dowdily, dowdiness, dowdy,