“究竟” and “到底” are two important words in the HSK exam. This is the words analysis about these two words for the free Chinese lesson.
＜adverb＞ investigate and stress on the nature or characteristic of things.
“究竟” and “到底” are quite close in meaning and they are exchangeable generally. Therefore, it is little hard to distinguish the two words in the HSK exam. And we will introduce the similarity as following in free Chinese lesson.
You can see it in the HSK exam that both can be use in the interrogative sentence without “吗” or in the sentences implying interrogative meaning, indicating the interrogative mood of investigating.
For example:
你究竟/到底怎么了？ 你怎么不说话呀？
光天化日之下抢东西，究竟/到底还有没有王法了？
(Robbing in broad daylight, is there actually the law?)
这种做法究竟/到底行不可行，我也说不好。
她也不知道这样爱下去究竟/到底会是什么结果。
Both can be used in declarative sentence to stress on the tone. Usually the sentence implies evaluation which means “no matter how…, it is still…” They are mainly used in the sentence of “是”. It is often shown in the HSK exam.
For example:
究竟/到底是城里的孩子，你看人家多大方呀！
他究竟/到底是个孩子，怎么可能把事情想得那么周全？
(After all, he is a child. How can he be so considerate?)
这里究竟/到底是省城，跟乡下就是不一样。
究竟/到底是春天了，刮这么大的风，还是暖暖的。
Slight difference between “究竟” and “到底”. The HSK exam often involves the difference of these two words. In the HSK exam, these two words are often distinguished in flavour.
In flavour: since “究竟” has the flavour of written language, it is used in written language; while “到底” has strong flavour of spoken language, it is used in colloquial language.
In interrogative mood, the investigating angle of the two words is slightly different. “究竟” emphasizes the cause of a matter, or to make clear what happens; while “到底” mainly means to make a profound inquiry. It is an important part in the HSK exam.
Other usages in the HSK exam for the free Chinese lesson
In the HSK exam ,“到底” indicates that after all the changes or complications something is realized in the end; “究竟” doesn’t indicate this.
For example:
卫星到底发射成功了。
你到底来了，我等你等得好辛苦啊！
(You’ve come in the end. I’ve been waiting for you so painstakingly.)
他用了三天三夜的时间，到底把设计图拿出来了。
* 卫星究竟发射成功了。
* 他用了三天三夜的时间，究竟把设计图拿出来了。
In the HSK exam, “究竟” is also used as a noun, indicating (result), (all the details), and to be used as object. In structure, it composes the pattern “verb+个+究竟” is not used in this way.
For example:
你不是想探个究竟吗？来，我告诉你。
(You want to find what actually happened. Well, let me tell you the truth.)
(门外吵吵闹闹的)她推开门，想看个究竟。
你去把他叫来，我非问出个究竟来不可。
(Go to get him here. I’ll ask him what on earth he has done.)
* 你不是想探个到底吗？来，我告诉你。
* (门外吵吵闹闹的)她推开门，想看个到底。
* 你去把他叫来，我非问出个到底来不可