Get to work! Don't sit ....... doing nothing

Analyze the question: The sentence is "Get to work! Don't sit ....... doing nothing." We need the preposition or particle that goes with "sit" to show someone is idle and wasting time.

Explain the concept: This question tests phrasal verbs. The meaning changes with the particle that follows the verb:

• sit about / sit around = stay idle, doing nothing useful
• sit up = rise from lying down, or stay awake late
• sit on = serve on a committee, or delay dealing with something
• sit by = watch something happen without taking action. It is usually followed by a clause, as in "sit by and watch."

Solution, option by option:

1. A. about: "Don't sit about doing nothing" is natural and common. It means don't be lazy or idle. ✔
2. B. up: "Don't sit up doing nothing" would mean staying awake, which doesn't fit the idea of getting to work.
3. C. on: "Don't sit on doing nothing" is not a standard expression here.
4. D. by: "sit by" suggests passively watching something happen. It would need "and" (e.g., "sit by and do nothing"), so it is awkward here.

Answer: The sentence calls for idleness, so A. about is correct.

Tip: "Sit about/around" means being idle, and you can link it to "loiter about." For "sit by," remember it usually appears as "sit by and watch/do nothing" (standing aside while something happens).