Acute onset cough

main purpose: 1. Taking the average number of coughs per hour within 24 hours as an index, evaluate the efficacy of QR052107B tablets compared with placebo in patients with subacute cough on D10. Secondary purpose: 1. In the subacute cough patients with an average cough times ≥ 20 times per hour within 24 hours in the baseline period, use the average cough times per hour within 24 hours as an index to evaluate the efficacy of QR052107B tablets compared with placebo on D4 and D10. 2. Taking the average number of coughs per hour in 24 hours as an index, evaluate the efficacy of QR052107B tablets compared with placebo in patients with subacute cough at D4. 3. Taking the average number of coughs per hour when awake as an index, evaluate the efficacy of QR052107B tablets compared with placebo in patients with subacute cough at D4 and D10. /4. Taking the cough severity VAS score as the efficacy index, evaluate the efficacy of QR052107B tablets compared with placebo in patients with subacute cough at D4 and D10. 4. Using the Leicester cough score as an index, evaluate the efficacy of QR052107B tablets compared with placebo in patients with subacute cough at D4 and D10. 5. Using sleep VAS score as an index, evaluate the efficacy of QR052107B tablets compared with placebo on D4 and D10. 6. To evaluate the safety and tolerability of QR052107B tablets in patients with subacute cough.