While each box contains a beacon, the unit only has enough battery power to transmit a signal for 30 days.
虽然每个盒子里都有一个信标，但这个装置的电池只能够传输30天信号。
2
Malls and big-box stores have proliferated, while many older urban shopping districts have declined.
大型购物中心和大超市数量激增，而许多比较老式的城市购物区则衰落了。
《柯林斯英汉双解大词典》
3
While boasting annual box-office revenue increases for nine straight years, largely due to increased ticket prices, the number of actual tickets sold has declined for the second year in a row.