Institution: জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় (JKKNIU) Exam: ক ইউনিট || জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় || 2013
Topic: Right Form of Verb, Subject: English Grammar (ইংরেজি গ্রামার)

Best Answer Explained in Below-:

The question "Do you know when--------?" requires a specific structure to complete it correctly. The correct choice is A) "the class starts." This option uses the simple present tense "starts," which is appropriate when inquiring about scheduled events or timeliness that is established as a fact.

Let's break down why the other options are incorrect:

B) "does the class start" is a question format, but since the sentence begins with "Do you know when," it calls for a statement rather than a question.

C) "will the class start" suggests future tense, which could imply uncertainty about the timing. However, "when" in the prompt implies there is a defined moment in time the question seeks, making the present tense more fitting.

D) "is the class" also lacks the necessary action word (verb) to complete the phrase meaningfully, leaving it unclear.

In summary, the phrase "the class starts" completes the sentence logically and grammatically, fitting the context of the inquiry about a specific event's timing.