it is time to do

该做…了

isolate, isolated, isolation, isolation hospital, isolation ward, isolationism, isolationist, isometric, isomorph, isomorphic, isosceles, isotherm, isotope, issue, issue from, isthmus, it, It goes without saying that, it happens that, it is likely that, it is no use doing..., it never entered one's mind, it seems that, it'd, it'll, it's, it's up to sb. (to do), ita, Italian, Italianate, italic, italicize, italicise, italics, Italo-, Italy, itch, itching, itchy, item, itemize, itemize, itemise,