at regular intervals

每隔一定时间(距离)

at home, at intervals, at large, at last, at least, at leisure, at length, at longest, at lowest, at most, at night, at no time, at odds with, at once, at one time, at one's best, at other times, at peace, at present, at random, at sb's disposal, at sb.'s heels, at sea, at sight of, at stake, at table, at that, at that rate, at the back of, at the beginning of, at the best, at the cost of, at the expense of, at the instance of, at the latest, at the mercy of, at the moment, at the rate of, at the same time, at the thought of,