What are these ______ English? [ ]
A. on
B. in
C. to
D. with
答案：B
John felt when he heard the result.[ ]
A. discouraging; discouraged
B. discouraged; discouraging
C. discouraging; discouraging
D. discouraged; discouraged
线段AB=2cm，延长AB到C，使BC=AB，再延长BA到D，使BD=2AB，则线段BD的长为______cm．
