custom什么时候可数什么时候不可数数?网上好多说用作海关、关税的时候才可数。但是我书上有一个It is difficult to get another country's customs。译为“习惯”的时候也做复数啊那到底什么情况才是

custom什么时候可数什么时候不可数数?网上好多说用作海关、关税的时候才可数。但是我书上有一个It is difficult to get another country's customs。译为“习惯”的时候也做复数啊那到底什么情况才是
custom什么时候可数什么时候不可数数?
网上好多说用作海关、关税的时候才可数。但是我书上有一个It is difficult to get another country's customs。译为“习惯”的时候也做复数啊
那到底什么情况才是复数什么情况才是不可数....

custom什么时候可数什么时候不可数数?网上好多说用作海关、关税的时候才可数。但是我书上有一个It is difficult to get another country's customs。译为“习惯”的时候也做复数啊那到底什么情况才是
custom
/ ˈkʌstəm; ˋkʌstəm/ n
1.(a) [C,U] usual,generally accepted and long-established way of behaving or doing things 习俗; 风俗:It is difficult to get used to another country's customs.要适应另一国家的风俗习惯是很困难的.* the customs of the Eskimos 爱斯基摩人的风俗 * a slave to custom,ie sb who does what most people do and have always done 习俗的奴隶 * procedures laid down by ancient custom 依照古老的习俗制定的程序.(b) [C] thing that sb habitually does; practice 个人的习惯:It is my custom to rise early.早起是我的习惯.
2.regular purchases from a tradesman,shop,etc 经常向某商人、 商店等购物:We would like to have your custom,ie would like you to buy our goods.我们欢迎您经常惠顾.* We've lost a lot of custom since our prices went up,ie Fewer goods have been bought from us.自从提价以后,我们失去了许多顾客的生意.* I shall withdraw my custom (ie stop buying goods) from that shop.我不再去那家商店买东西了.
customs
/ ˈkʌstəmz; ˋkʌstəmz/ n [pl]
1.taxes payable to the Government on goods imported from other countries; import duties 进口税; 关税:pay customs on sth 为某物缴纳进口税.
2.(also the Customs) government department that collects these taxes 海关:The Customs have found heroin hidden in freight.海关查出了隐藏在货物中的海洛因.* How long does it take to get through customs?ie have one's baggage examined by customs officers at a port,airport,etc 海关检查要用多少时间?* [attrib 作定语] a customs officer,search,check 海关官员、 检查、 查验 * customs duty,formalities,etc 海关税、 手续等

在我的印象中解释为海关时不可数，解释为风俗的时候才可数的

Customs海关custom风俗,习性可数也可以不可数. 惠顾,光顾,是不可数的.