我了解only后面接状语时，若放在句首，后面的句子要用部分倒装。譬如：
only after ten years in the country did she gain her citizenship. 她在这个国家住了10年后才获得了公民身份。
但only后面接状语从句放在句首时的倒装极少见，但在在人教版高中英语教程必学五的Unit 1里有如此一句：
only if you put the sun there did the movements of the other planets in the sky make sense.
这里的 only 后面接的是if you put the sun there，这是一个条件状语从句。请老师说明 only 后接状语从句放在句首时的倒装。谢谢！
状语短语和状语从句都是状语，only修饰状语且置于句首时，其后的句子一般要用部分倒装的形式（不管 only 后面接的状语是短语还是从句）。譬如：
▲only+after引导的时间状语
only after you have reached eighteen can you join the army. 你只有年满十八岁之后才能参军。
only after they had discussed the matter for several hours did they reach a decision. 他们把问题讨论了几个小时后才得出结论。
▲only+if引导的时间状语
only if a teacher has given permission is a student allowed to enter this room. 只有得到教师的允许，学生才能进这间屋。
only if these conditions are fulfilled can the application proceed to the next stage. 只有满足这类条件，这个应用程序才能进行到下一步。
▲only+when引导的时间状语
only when the masses are fully mobilized can victory be won. 只有充分发动群众，才能获得胜利。
only when we landed did we see how badly the plane had been damaged. 大家只不过在着陆之后才看到飞机损毁的紧急程度。
▲关于 only 后接状语置于句首时不需要倒装的使用方法，请参考：
http://www.yygrammar.com/Article/201305/3222.html
