一、only引导的词组或句子放在句首作状语时，通常要用倒装结构。如
Onlyinthiswaycanyousolvetheproblem.
Onlyifyoustudyhardcanyoupasstheexam.
OnlythendidIrealizemymistake.
二、notonly...(butalso)出现在句首时，如果架连接的是两个句子，常用倒装。如
Notonlydidweloseallourmoney,butwealsocameclosetolosingourlives.
Notonlydidhespeakcorrectly,buthealsospokeeasily.
三、only放在不定式前面，常表示不愉快或出乎人们的意料的结果。如
Iwentallthewaytohishomeonlytofindhimeoutatameeting.
Ihurriedtothepostofficeonlytofinditclosed.
Shewenthomeonlytofindherhouseburglarized.
四、“too...to...”结构中，表示否定意思，但在“onlytoo...to...”结构中，onlytoo=very，表示肯定意思。如
Thepatientistooweaktowalk.
Weareonlytoowillingtodoitforyou.
Iamonlytoodelightedtoacceptyourkinginvitation.
五、在“oneof+复数名词+定语从句”的结构中，定语从句一般被看作修饰复数名词，谓语要用复数形式。但在“theonlyoneof+复数名词+定语从句”的结构中，定语从句却被看作修饰“theonlyone”，谓语动词要用单数形式。如
Thisisoneofthebestnovelsthathavebeenpublishedinthepasttwoyears.
Hewastheonlyoneoftheboyswhowasgivenaprize.
SheistheonlyoneofthegirlswhohasbeentotheUS.
六、Ifonly为虚拟语气的一种，表示愿望或一个未实现的条件，多用于感叹句，其主句常常省略。如
Ifonlyyoucouldhavebeenhereearlierthatday!
Ifonlytherewereforty-eightyhoursinaday.
