He has not married and will not marry in near future.
She is intelligent but her sister dull.
Both are compound sentences. But in both cases the usage of verb is different.
Why we have not used is in the second sentence after sister?
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
As John Lawler commented, this is a case of conjunction-reduction and Gapping.
(Grammar) (transformational grammar)a rule that reduces coordinate sentences, applied, for example, to convert John lives in Ireland, and Brian lives in Ireland into John and Brian live in Ireland.
In your first sentence (He has not married and will not marry in near future), the subject is He, and it is omitted by the same rule.
John stole a bike and sold it immediately.
is the same as:
John stole a bike, and he sold it immediately.
Your second sentence is a case of Gapping
Again from the same dictionary:
(Grammar) (in transformational grammar)a rule that deletes repetitions of a verb, as in the sentence Bill voted for Smith, Sam for McKay, and Dave for Harris
In the above example, the verb "voted" is deleted to avoid repetition:
Bill voted for Smith, Sam
votedfor McKay, and Dave votedfor Harris.
Gapping usually elides minimally a finite verb and further any non-finite verbs that are present. This material is "gapped" from the non-initial conjuncts of a coordinate structure. Gapping exists in many languages, but by no means in all of them, and gapping has been studied extensively and is therefore one of the more understood ellipsis mechanisms.Stripping is viewed as a particular manifestation of the gapping mechanism where just one remnant (instead of two or more) appears in the gapped/stripped conjunct.
- Some ate bread, and others [ate] rice. <=> Some ate bread, and others rice.
- Fred likes to pet the cat, and Sally [likes to pet] the dog. <=> Fred likes to pet the cat, and Sally the dog.
- Jim has been being observed by me, and Tom [has been being observed] by you. <=> Jim has been being observed by me, and Tom by you.
- Should I call you, or [should] you [call] me? <=> Should I call you, or you me?
- Linda had a beer, and Irvin [had] a coffee. <=> Linda had a beer, and Irvin a coffee.
Coming to your sentence, now it would be easier for you to understand why we have not used is after sister.
She is intelligent but her sister dull. <=> She is intelligent, but her sister is dull.
Go through the links provided below for more clear understanding.