这种情况通常是将特殊疑问词引导的名词性从句替换为特殊疑问词+不定时.
具体情况和例句如下:
whowhatwhichwhenwherehow后加不定式在句中可以做主语、宾语、表语等,但why后加动词原型,是特例:
1.主语
e.g.whenwewillstarthasnotbeendecided.可替换为Whentostarthasnotbeendecided.
何时动身还未决定.
2.宾语
e.g.Hedidnotknowwhetherheshouldgothereornot.替换为Hedidnotknowwhethertogothereornot.
他不知该不该去那.
3.表语
e.g.Thedifficultywashowwecouldcrosstheriver.替换为Thedifficultywashowtocrosstheriver.
困难在于怎样过河.
e.g.Thequestionwaswhereweshouldgo.替换为Thequestionwaswheretogo.
问题是去哪里?
4.双重宾语
e.g.Icantellyouwhereyoucangetthisbook.替换为Icantellyouwheretogetthisbook.
我能告诉你从哪搞到这本书.
e.g.IaskedhimhowIcouldlearnEnglish.替换为IaskedhimhowtolearnEnglish.
我告诉他怎样学好英语.
5.有时疑问词前可用介词
e.g.IhavenoideaofhowIcandoit.替换为Ihavenoideaofhowtodoit.