状语从句放在主句前都要用逗号隔开吗？？

1）状语从句出现在倒装句中，并位于句首时，可以用逗号隔开也可以不隔开。用逗号隔开，从某种程度上来说更符合习惯
例题：Only when your identity has been checked, _____.
A. you are allowed in B. you will be allowed in C. will you allow in D. will you be allowed in
其他例句 Only when we had studied the data again did we realize that there was a mistake. 只有当我们再次研究了这些数据的时候， 我们才意识到出了一个错。Only because there were some cancelled bookings did he get some tickets in the end. 一些预订被取消了， 他才得以买到了几张票。 由于状语从句位于句首或句中通常用逗号隔开，所以Only when your identity has been checked，will you be allowed in.用逗号隔开，从某种程度上来说更符合习惯
2）如果only后面只是跟一个方式状语，不是从句，通常不隔开
例题 Only in this way ____ to make improvements in the operating system. A. you can hope B. you did hope C. can you hope D. did you hope