对某人很重要 be important to sb ; Is important for a person ; Is very important to someone

做某事对某人很重要 be important for sb. to do

某事对某人很重要 Sth is/are important to sb

对某人来说很重要 be important to sb ; It's important to sb ; be important to ; be important for sb

某事对某人来说很重要 sth is important to sb