Explanation

Before & Within

Before = point of time

Within = period of time

Please go there before Friday.

Finish it within two days means اس کو دو دنوں میں مکمل کرو

Explanation

Generally familiar is followed by with.

With is a preposition here.

He is familiar with me وہ مجھ سے واقف ہے

Explanation

"Can" is one of the most commonly used modal verbs in English. It can be used to express ability or opportunity, to request or offer permission, and to show possibility or impossibility

Explanation

He is speaking at the back of his best friend.

At the back of means کے پچھلے حصے میں

Explanation

We generally use preposition By before transports like by bus, by car, by air etc. 

Explanation

By the stroke of luck, the troops prevailed, avoiding a crushing defeat.

Explanation

This sentence belongs to Future Perfect Tense.

Formula: Subject + will + have + 3rd form of a verb + object.

Explanation

The word "unless" is an adverb which means جب تک

Explanation

He is ignorant to what he pretends to know.

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Explanation

Use a comma before while in the middle of a sentence when you mean “whereas” or “although.