A:干炼 凝炼 简练 锻炼
B:启事 启示 启用 起用
C:殒落 坠落 堕落 脱落
D:间谍 喋血 通谍 谍报
Please post this letter in the post office nearby, and __________, I will get two tickets in the train station. ( )
根据句意及首字母提示填写单词。