Explanation

He has left for London means وہ لندن روانہ ہوچکا ہے۔

We should use past indefinite tense for a point of time.

Explanation

We should use past indefinite tense for a point of time.

Discover is a verb which means دریافت کرنا

Explanation

We should use past indefinite tense for a point of time.

He has gone means وہ جاچکا ہے۔ 

Explanation

Nelson Mandela is known for his struggle against racism in South Africa

He was a South African anti-apartheid revolutionary, political leader

He served as President of South Africa from 1994 to 1999.

Explanation

The militaries of India and Pakistan are taking part in a mega anti-terror drill of the Shanghai Cooperation Organisation  in Russia aimed at expanding cooperation among the member countries to deal with the growing menace of terrorism and extremism

Explanation

Explanation

Tidings are plural noun.

Tidings mean information.

Tidings means معلومات

Explanation

Gallows means پھانسی

Gallows is a singular noun.

Explanation

A large number = plural noun

The large number = singular noun

Explanation

Although the word deer are plural noun but the word this indicates singular.