The correct option to fill in the blank in the sentence "The meeting starts .... two o'clock. Please be punctual" is D. at. Explanation of the Correct Answer

1. Understanding Prepositions of Time:
2. In English, we use specific prepositions to indicate time. The preposition "at" is commonly used to refer to precise times on the clock. For example, we say "at 5 PM," "at noon," or "at midnight."
3. Context of the Sentence:
4. The sentence is indicating a specific time when the meeting will start, which is "two o'clock." Since "two o'clock" is a specific time, the correct preposition to use is "at." Therefore, the complete sentence reads: "The meeting starts at two o'clock. Please be punctual."

Why the Other Options Are Incorrect

• A. about:
• The word "about" suggests an approximation rather than a specific time. If we said "The meeting starts about two o'clock," it would imply that the meeting might start a little before or after two o'clock, which is not the intended meaning in this context. The instruction to "be punctual" indicates that the meeting time is exact.
• B. in:
• The preposition "in" is used for longer periods of time, such as months, years, or parts of the day. For example, we say "in the morning," "in July," or "in 2023." It does not work with specific times on the clock. Therefore, "The meeting starts in two o'clock" is grammatically incorrect.
• C. on:
• The preposition "on" is used for days and dates. For example, we say "on Monday," "on Christmas Day," or "on the 1st of January." It does not apply to specific times. Thus, "The meeting starts on two o'clock" is also incorrect.

Summary of Key Points

• The correct preposition for specific times is "at."
• "About" indicates approximation, which is not suitable here.
• "In" is used for longer time frames, not specific times.
• "On" is reserved for days and dates, not clock times.

Revision Summary

• Use "at" for specific times (e.g., "at 3 PM").
• "About" indicates an approximation, not exactness.
• "In" is for longer periods (e.g., "in the afternoon").
• "On" is for days and dates (e.g., "on Friday").

By understanding these distinctions, you can choose the correct prepositions in various contexts, enhancing your English language skills.