Question

either robin or his uncle _____ sure to be there (is,are)​

Answer 1

Answer:

are

Explanation:

if we say is it is not correct just like either robin or his uncle is sure to be there no are sure to be there

Answer 2

Answer:

Is

Reason :

Are is not the answers because

Any one of Robin and his uncle is sure

Which represent 1 person that is singular so we use is in the above blank

Hope this is helpful to you mate