add by mixing or blending on or attaching; "work in the butter and the dough will get the right consistency"; "In his speech, the presidential candidate worked in a lot of learned words"
occur between other event or between certain points of time; "the war intervened between the birth of her two children"
get involved, so as to alter or hinder an action, or through force or threat of force; "Why did the U.S. not intervene earlier in WW II?"
be placed or located between other things or extend between spaces and events; "This interludes intervenes between the two movements"; "Eight days intervened"