1. Stars are only visible when the sky is dark.
   只有在天空不亮时才看得见星星。
2. was merciful only when mercy was expedient.
   只有仁慈对自己有利时才是仁慈的
3. Be careful when you try on the dress- it's only pinned.
   试穿这件连衣裙要小心--只是用针别住的.
4. Lorries may only park here when loading or unloading.
   卡车非装卸货物时不得在此停车.
5. The prince assumed power when he was only fifteen.
   王子在十五岁时就掌权了。

　1个副词解释