The CHILDES command "combo" performs searches with Boolean operators like "or" or "not". Combo also manages searches in which a word (or set of words) must follow a target word - immediately or later. 

The following command searches for the word "want" followed immediately by the word "to" in Adam's first file:

combo +s"want"^"to" adam01.cha

The following command searches for any word in the file "wh.txt" immediately followed by the word "have":

combo +s@wh.txt^"have" adam01.cha

The following command searches for any word in the file "wh.txt" immediately followed by any word in the file "aux.txt":

combo +s@ wh.txt^@aux.txt adam01.cha

The following command searches for "want" followed either immediately or later by the word "to":

combo +s"want"^*^"to" adam01.cha

The following list shows some common operators used with combo:

• ^: Immediately followed by
• +: OR
• !: NOT
• *: Repeated character

Exercise
Adult speakers of most varieties of English produce oblique "Wh-questions" by placing the "Wh-word" to the left and by performing "subject-auxiliary inversion" (SAI). Answer the following questions on the Eve corpus:

1. Do children acquiring English also consistently perform SAI in "Wh-questions" from the earliest period? If not, what is the general structure of their early "Wh-questions?" 
    
    
    
2. Given that children acquiring English often omit grammatical subjects, how would you know whether they perform SAI?)