有种观点认为，一个句子只能有一个地点状语，一个时间状语。因此，当一个句子中出现二个或以上表示地点或时间的词、短语、或从句时，如果它们之间不是并列关系或同位关系，则必要是互相修饰关系，即其中一个是定语，修饰前面的时间或地点名词。例如下面两个句子：

Many people eat in restaurants in London.

Tom broke his leg last month when he was playing football.

这种观点认为第一句中的 in London 只可能是 restaurants 的定语，不可能是状语。第二句中的 when 从句只可能是 last year 的定语从句，不可能是状语从句。

我认为除了并列、同位和修饰三种关系外，二个或以上的时间或地点结构之间完全可能存在第四种关系---等级关系。即它们可以从不同的角度、以不同的精确度分别修饰谓语动词或分句，而他们之间并非互相修饰关系。即一个句子可以有二个或以上的时间状语。最近在夸克的《英语语法大全》中找到了关于这种等级关系的论述，特转贴在这里，供英语老师和有兴趣的网友参考。

夸克《英语语法大全》英文版P.519-520.

Hierarchical relationship

8.45 It often happens that two spatial adjuncts enter into a contextual relation of hierarchy. This can occur where both adjuncts are of the same semantic class but of different grammatical functions (the one being a sentence adjunct, the other a predication adjunct). For example, with two position adjuncts:

Many people eat in restaurants in London.

The order here satisfies both the grammatical requirement (that the sentence adjunct be more peripheral than the predication one) and the logical requirement (that the smaller location be stated before the larger in which it is placed). But if the sentence adjunct is expressed with an adverb indicating that it is relatively 'given' (cf l8.8ff), the order may be reversed:

Many people eat here/there in restaurants.

Just as on grammatical grounds, it can only be the sentence adjunct that can appear at ('In London, many people . . .'), so also on logical grounds, the lower member in the hierarchy cannot dominate the higher:

*In restaurants, many people eat in London.

夸克《英语语法大全》英文版P.533

Time-position adjuncts can be in a hierarchical relationship:

They were here late [A1] last night [A2].

I'll see you at nine [A1] on Monday [A2].

I spoke to her earlier [A1] today [A2].

We'll meet tonight [A1] after the show [A2].

The order of the adjuncts at end position depends in part on information focus，but the tendency is for the superordinate adjunct (the one denoting the more extended period) to come last. However, as in the last example above, the order may be reversed if the other adjunct is longer, nonetheless preserving the essential partitive relation between the two.

Compare also:

I was in New York last year [A1] before the first snow fell [A2].

They became drunk today [A1] within a very short time [A2].

So far, however, we have looked at hierarchically related adjuncts which are both predication adjuncts. If the superordinate item is a sentence adjunct, it can appear in initial position, and the relation is no longer so essentially partitive; as can be seen from the parenthesized additions in the following:

Last night they were here late (again).

On Monday I'll see you at nine (as usual).