Introducing English Linguistics

wh-question. In the second sentence, did occurs with the phrasal
verb pick up.
Why did the Vietnamese ultimately 
fight on? 
(MICASE LES495JU063O)
I did not 
pick her up
(ICE-GB S1A-020 004)
In both of the examples above, did has no real meaning: it is merely used
to form a question or negate a sentence. For this reason, in some gram-
mars it is referred to as dummy do. The exact details of why the sentences
above are formed the way that they are will be discussed in the next sec-
tion on clauses and sentence types.
Do has one additional use. In the example below, it is used to emphasize
the fact that the speaker does indeed like to hear the addressee talk:
I do like to hear you talk. 
(BNC GO7 625)
Without do – I like to hear you talk – the statement is far less emphatic.
There are two types of modal auxiliaries: central and phrasal. Table 5.6
lists all the central modals in English, plus some select phrasal modals. An
expression such as be going to is considered a modal because, like will, it
express future time and occurs at the beginning of the verb phrase. In the
examples below, both will and  is going to mark future time and occur
before the lexical verb leave:
Joanne’s commitment to the next 12 months will
leave her little time
for the hobbies that she enjoyed before tennis came along.
(BNC AOV 1096)
Joanne’s commitment to the next 12 months is going to
leave her little
time for ... 
English syntax
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