事情一开始进展得很顺利,但后来我们遇到了困难
I understand the meaning of the sentence, but I don't understand what is "一" doing in there? Could it be dropped? Would it change the meaning? Is it a part of the "一开始" as a phrase?
一 in this construction has the meaning of ”once”.
Once the business got started it was very successful, but later on we encountered difficulties.
Another example: 一看他的样子就知道他是个骗子。
Here, 一 should not be parsed by itself, but instead put together with 开始 to form the phrase 一开始, which means "at the beginning" or "initially". So the correct translation would be:
事情一开始进展得很顺利,但后来我们遇到了困难
At the beginning, everything was going smoothly, but later we encountered difficulties.
Here are some more examples:
一开始,我不喜欢她。后来,我爱上了她。 At the beginning, I didn't like her. Later, I fell in love with her.
我一开始以为你很笨,后来发现其实你很聪明! Initially, I thought you were dumb, but later I discovered that you are actually very smart.
Hope that helps! Happy learning.
I somehow feel 一开始 is a bit earlier than if you use 开始 in term of time in the example "事情一开始进展得很顺利,但后来我们遇到了困难". So I tend to translate 一开始 as "at the very beginning" vs "at the beginning".
Maybe there is a subtle difference between 一 in 一开始 and 'once'. I feel that 一 emphasizes more about what is happening at that moment.
I tend to understand 一开始 as a whole, which means "at the beginning". You can omit the 一 in most situations without changing the meaning much. However, adding 一 (which alone could be interpreted as "once" or "as soon as") puts an emphasis on “beginning”, giving a hint that the speaker might later want to compare it with how things are like " in the end", or to emphasize something happened very early. Also, in some sentence structures, it may not be so obvious whether 开始 should be parsed as the verb "to begin" or "in the beginning" at the first glance, whereas 一开始 invokes no such ambiguity.
I personally use 一开始 much more often than 开始.