Neither you nor your sister should . . . . . . . . to them.

Solution (By Examveda Team)

The sentence has the words "should" and "neither...nor".

Let's look at two important grammar rules here:

1. Rule 1: Modal Verbs (like "should")
Words like should, can, could, will, would, may, might, must are called modal verbs.
After a modal verb, we always use the base form of the verb (the simplest form of the verb, without 's', 'ed', or 'ing').
For example: "You should talk." (NOT "should talks" or "should talked" or "should talking").

2. Rule 2: Neither...nor
When you use "neither...nor", the verb usually agrees with the subject that is closest to the verb.
In your sentence: "Neither you nor your sister should..."
The subject closest to the blank is "your sister" (which is singular).
However, Rule 1 (the modal verb "should") is the strongest rule here! It decides the form of the verb immediately.

So, combining both:
Because we have "should", we *must* use the base form of the verb.

Let's look at the options:
* Option A: talk - This is the base form of the verb. This fits perfectly with "should".
* Option B: talks - This form is used for third-person singular in the simple present tense (e.g., "She talks"). It does not follow "should".
* Option C: talked - This is the past tense form. It does not follow "should".
* Option D: talking - This is the '-ing' form. It does not follow "should" directly (it would need "should be talking" for example).

Therefore, the correct answer is Option A: talk.
The complete sentence is: "Neither you nor your sister should talk to them."