48 Chapter 3 Verbs, tense, aspect, and mood
Although indirect reported speech represents the most obvious case, backshift
also happens quite generally in constructions where one clause is embedded within
a larger one containing a preterite verb:
[39] i Stacy didn 't know that Kim had blue eyes.
ii I wondered at the time whether they were genuine.
iii I wish I knew if these paintings were genuine.All the underlined verbs have backshifted tense. Notice in particular that the knew of
[iii] is actually a modal preterite, and doesn't refer to past time at all; but it still pro
vides a context in which backshift can take place. So backshift can't be understood
at all on the basis of some simple idea about preterite tenses referring to past time;
it's a special grammatical principle about the use of the preterite tense inflection.
6 The perfect
The perfect is a past tense that is marked by means of an auxiliary verb
rather than by inflection, like the preterite. The auxiliary is have, which is followed by
a past participle. Examples are given in [40] along with their non-perfect counterparts:
[40] PERFECT NON-PERFECT
a. She has been ill. b. She iJ. ill.
u a. She had left town. b. She !&.f1 town.
III a. She is said to have spoken fluent Greek. b. She is said to speak fluent Greek.In [ia] and [iia] the auxiliary have is itself inflected for primary tense, has being
a present tense form, had a preterite. These constructions thus have compound
tense: [ia] is a present perfect, [iia] a preterite perfect. In [iiia] have is in the plain
form, so this time there is no primary tense, no compound tense.
In all three cases the perfect encodes past time meaning. This is very obvious in
[i] and [iii] where the [a] examples refer to past time and the [b] ones to present time
but we will see below that it also holds for [ii].
The present perfect is the most frequent of the constructions in [40], and we will
begin with this even though the combination of present and past tenses makes it the
most complex of the three.6.1 The present perfect
The present perfect, like the simple preterite (the non-perfect preterite)
in its central use, locates the situation, or part of it, in past time:[41] PRESENT PERFECT SIMPLE PRETERITE
a. She has read your letter. b. She read your letter.
The difference in meaning results from the fact that the present perfect is a com
pound tense combining past and present, whereas the simple preterite is purely a