Subject: Sindh University Past Papers and Syllabus

Explanation
Tense : Present simple (They buy) Passive structure : Object + is/are + past participle + by + subject " Flowers " is plural → use " are " Past participle of buy is bought Correct passive voice: Beautiful flowers are bought by them.

Explanation
This is an interrogative sentence (yes/no question). " Did you see " → "I had seen" (past simple → past perfect) " my " → "her" " this room " → "that room" " said to " → "asked" We can use " if " or " whether " in indirect questions. So both are correct : She asked me whether I had seen her daughter in that room. She asked me if I had seen her daughter in that room.

Explanation
The sentence expresses a wish or prayer , so in indirect narration we use " prayed ". Changes: " May " → "might" " here " → "there" So, the correct indirect narration is: They prayed that train might reach there in time.

Explanation
This is a question sentence in indirect narration. Changes : " said to " → " asked " " were you sitting " → " they had been sitting " (past continuous → past perfect continuous) " here " → " there " So, the correct narration is: He asked them why they had been sitting there.

Explanation
Direct speech: " I broke my pencil today ." Changes in indirect speech: " I " → "she" " broke " (past) → "had broken" (past perfect) " my " → "her" " today " → "that day" So, the correct indirect narration is: She said to him that she had broken her pencil that day.

Explanation
Direct speech : " You are my best friend. " Indirect speech : Pronouns and tense change: " You " → " I " " are " (present) → " was " (past) " my " → " his " So the correct narration is: He said that I was his best friend.

Explanation
The hertz is the unit of frequency  of one cycle per second.   symbol: hertz (Hz) Hertz in honor of the German physicist Heinrich Hertz hertz in the International System of Units (SI) frequency i s defined as one cycle per second ***

Explanation
Imperative sentence → passive voice starts with " Let " Base verb " strike off " → past participle is " struck off " Structure : Let + object + be + past participle Correct passive voice: Let his name be struck off.

Explanation
Exponential notation (scientific notation) is used to express very small (e.g., 0.0000001) or very large (e.g., 1000000000) quantities compactly by representing numbers as powers of 10 . Key Information : Format : a × 10^n, where 1 ≤ a < 10 and n is an integer. Used for very large or very small numbers . Examples: Large number : 6.022 × 10^23 ( Avogadro's number ) Small number : 1.6 × 10^-19 ( Charge of an electron )

Explanation
Marconi  invented  Radio . Radio was invented in  1895 . Guglielmo Marconi was an  Italian  inventor.  *****