130 could waswere allowed to用来表示过去的许可

 

could也能表示过去的一般的允许:

On Sundays we could=were allowed tostay up late

星期天晚上我们能到较晚才睡。

当某一具体行为获准并付诸实施时,就必须用waswere allowed代替could

I had a visa so I was allowed to cross the frontier

我有签证,所以我被允许越过边界。

couldn't的用法比could要稍为广泛一些:

We couldn't bring our dog into the restaurant

我们不能把狗带进饭馆里。

与此相反的意思应当用allow表示:

We were allowed to bring

允许我们把狗带进……,

如欲使用完成时和被动语态,则必须用 allowed

Since his accident he hasn't been allowed to drive

自从他出了车祸以后就不允许他再开车了。

As a child he had been allowed to do exactly what he liked

他小时候,容许他爱干什么就干什么。

(关于mightcould在间接引语中的用法,参见第129A。)