Question

英语中Only放句首的这种情况需要倒装么？

Answer 1

1.副词only置于句首， 强调方式状语、 条件状语、  
地点状语、 时间状语等状语时， 主句要进行部分
倒装。例如：  
Only in a big city was it possible to buy new
wheelchairs. 只有在大城市里才能买到新轮椅。
2.如果放于句首的only所修饰的不是状语时，  
该句不用倒装。例如：  
Only John can save me. 只有约翰能够救我。  
3.如果被only所强调的状语为状语从句，  
该状语从句不倒装， 只对主句进行倒装。如：
Only when we had studied the data again  
did we realize that there was a mistake.  

only + 状语放在句首,要部分倒装。
Only on such a trip can you learn so much about European artists.  (介词短语)
Only by this means is it possible to explain it.  (介词短语)
Only then did I realize the importance of English.  (副词)
Only when the war was over was he able to get happily back to work. (从句)

Answer 2

英语中Only放句首，要接三种形式才符合后面采用部分倒装的要求：
副词，介词短语，状语从句。例如：
Only then did he realise he had lost his key to the door.
Only by working hard can we learn a foreign langguage.
Only when I reread the poem did I find its beauty.
你所给的例句虽然有逗号，但并不妨碍倒装的使用，因此，还应该使用倒装——
Only through despair can we find nirvana.

但是，这句话表达并不清晰，因为有歧义。
可以修改为：
Only by going through（ ， ）despair can we find nirvana.

祝你开心如意！