Only half-hour intervals were allowed them for meals.是什么意思？

Only half-hour intervals were allowed them for meals.

只给他们半小时的时间吃饭。

only

adj. 唯一的，仅有的，最好的，最适当的；adv. 只，仅仅，结果却，不料；conj. 但是，可是，要不是；

例句
Outsiders who wed islanders are given only three years' right of abode at first.
岛外的人和岛民结婚之初只能获得三年的居住权。

intervals

n. [军事]间隔( interval的名词复数 )，间隔时间，[数学]区间，（戏剧、电影或音乐会的）幕间休息；

例句
She woke him for his medicines at intervals throughout the night.
她夜里每隔一段时间就叫他起来服药。

were

be的过去时复数和第二人称单数形式，有时代替 was,用于条件从句、动词 wish 之后等；

例句
Shops, houses, and vehicles were set ablaze.
店铺、房子和车辆全都陷于火海。

allowed

adj. [计]容许的；v. 允许( allow的过去式和过去分词 )，承认，酌增，接受；

例句
He was not allowed access to a lawyer.
他未被获准见律师。

them

pron. 他们，她们，它们；

例句
I take care of them to the best of my abilities...
我尽我所能地照顾他们。

for

prep. 为，为了，倾向于，关于，当作；conj. 因为，由于；

例句
I've come looking for a bit of advice.
我特来讨教。

meals

n. 餐( meal的名词复数 )，进餐时间，一餐所吃的食物，谷物粗粉（用作饲料或加工面粉）；

例句
There's always a wide selection of delicious meals to choose from...
总是有很多美味可口的饭菜可供选择。