Final answer:
The negative formal command (ud) of 'cerrar' is no cierre. This is formed by using the present subjunctive form of the verb, which is 'cierre' for 'cerrar', and adding 'no' before it.
Step-by-step explanation:
The negative formal command (ud) of the verb cerrar in Spanish is no cierre. This command form is used to tell someone respectfully to not do something, in this case, to not close something. The structure for creating a negative formal command in Spanish involves placing 'no' before the third person singular present subjunctive form of the verb. For the verb cerrar, which is an 'e' to 'ie' stem-changing verb, the present subjunctive form is cierre. Therefore, the negative formal command is formed by prefixing it with 'no'.
To construct a negative formal command for other verbs, you would typically take the yo form of the present indicative, drop the 'o,' and add the opposite vowel present subjunctive ending. For -ar verbs, such as hablar, you would add '-e' (no hable), and for -er and -ir verbs, like comer and escribir, you would add '-a' (no coma, no escriba). These commands are particularly useful in formal settings or when addressing someone with whom one is not familiar.