根据《柯林斯英汉双解大词典 》：
ADJ Serious problems or situations are very bad and cause people to be worried or afraid. 严重的; 危急的
seriously ADV 严重地; 危急地
ADJ Serious matters are important and deserve careful and thoughtful consideration. 重要的
ADJ When important matters are dealt with in a serious way, they are given careful and thoughtful consideration. 认真的; 严肃的
seriously ADV 认真地; 严肃地 [ADV with v]
ADJ Serious music or literature requires concentration to understand or appreciate it. 严肃的 [ADJ n]
ADJ If someone is serious about something, they are sincere about what they are saying, doing, or intending to do. 真心的; 郑重的
seriously ADV 真心地; 郑重地
ADJ Serious people are thoughtful and quiet, and do not laugh very often. 严肃的
seriously ADV 严肃地 [ADV with v][1]