Explanation

"Worth seeing" correctly describes something valuable or interesting to look at.

The structure "a site worth seeing" is grammatically correct and commonly used.

Explanation

I have never seen him after that unfortunate incident.

اس ناخوشگوار واقعے کے بعد میں نے اسے کبھی نہیں دیکھا

The phrase "I have never seen him" implies the last meeting was before a specific point in time.

"After" fits best to indicate that the incident marks the point since which there has been no meeting.

Explanation

"Since" is used to indicate the time from a past event up to now or another point in the past.

The sentence refers to events that occurred after the speaker left school — so "since I left the school" is correct.

Explanation

The matter is between him and me

معاملہ اس کے اور میرے درمیان ہے

"Between" is a preposition and is followed by objective pronouns.

"Him" and "me" are correct objective forms.

Explanation

"Have had" is the correct present perfect tense to show ownership continuing from the past to the present.

"Have been" requires a verb ending in -ing, which is not present here.

Explanation

The perfect square among these is 81 (since 9 × 9 = 81).

Explanation

A nucleotide, the basic unit of DNA, consists of a 5-carbon sugar (deoxyribose), a nitrogenous base, and a phosphate group.

These components link together to form the DNA's double-helix structure.

Explanation

 B.F. Skinner proposed the Behaviorist Theory, suggesting that language is learned through conditioning, imitation, and reinforcement, not innate mechanisms.

Explanation

 The Nativist Theory, proposed by Noam Chomsky, argues that humans are born with an innate capacity for language through a mental mechanism called the Language Acquisition Device (LAD).

Explanation

Centrioles play a crucial role in organizing the spindle fibers during cell division, specifically in mitosis and meiosis.

They help in the formation of the spindle apparatus, ensuring proper chromosome separation.