“越……越……”means that the degree of something changes along with the development of the situation. Thus, where “越来越”focuses on time, “越……越……”focuses on a change of situation. “越……越……”is a little bit more complicated than “越来越” , and it has three common sentence structures：
(1) Subject +越+Verb+越+adjective / Verb
In this structure, we put a verb after the first”越”(yuè), and put an adjective or a mental verb after the second ”越”. It indicates that the degree of the adjective or the mental verb changes along with the development of the first verb.
1). 汉语越学越难。(Hànyǔ yuè xué yuè ná)
The more you learn Chinese, the more difficult you will find it.
2). 这个问题越想越复杂。(Zhège wèntí yuè xiăng yuè fù zá.)
The more you think about the problem, the more complicated
it will seem.
(2) Subject + 越 + adjective1 + 越 + adjective2
In this structure, we put two different adjectives separately after each ”越”. That mean the degree of the first adjective leads to the changes of the second adjective.
1). 朋友越多越好。(Péngyou yuè duō yuè hăo.)
It’s better to have more friends.
2). 苹果越红越甜。(Píngguŏ yuè hóng yuè tián. )
The more red the apple looks, the more sweet it tastes.
(3) Subject1 + 越 + adjective1/Verb, Subject2 + 越 + adjective2/mental verb (+……)
In this structure, there are two subjects. The degree of the second subject varies along with the situation of the first subject.
1).他越解释，我们越糊涂。(Tā yuè jiĕshì, wŏmen yuè hú)
The more he explained, the more confused we felt.
2). 咖啡越苦，我越喜欢喝。(Kāfēi yuè kǔ, wŏ yuè xĭhuan hē.)
The more bitter the coffee, the more I like to drink it.