Completion of sentences: From each question, choose from the most suitable to complete the sentence given.

Here are the completions for the French sentences:

1. Elles mangent du pain.

   • "Pain" (bread) is a masculine singular noun. To express "some bread" with the verb "manger" (to eat), we use the partitive article "du".
   • The correct option is C.
   • $\boxed{\text{C. Du}}$

2. Nous écrivons aux tableaux.

   • "Tableaux" (boards/paintings) is a masculine plural noun. The preposition "à" (on/to) combined with the plural definite article "les" (the) contracts to "aux".
   • The correct option is B.
   • $\boxed{\text{B. aux}}$

3. L' enfant dort sur la table.

   • "Enfant" (child) is a singular noun that starts with a vowel. The definite article "le" or "la" contracts to "l'" before a vowel.
   • The correct option is C.
   • $\boxed{\text{C. L'}}$

4. Voici un stylo. C'est mon stylo.

   • "Stylo" (pen) is a masculine singular noun. "Mon" is the masculine singular possessive adjective for "my".
   • The correct option is A.
   • $\boxed{\text{A. Mon}}$

5. Tu connais ta tante?

   • "Tante" (aunt) is a feminine singular noun. "Ta" is the feminine singular possessive adjective for "your" (informal "tu").
   • The correct option is C.
   • $\boxed{\text{C. ta}}$

6. Mes ............ sont ses frères.

   • "Frères" (brothers) is a masculine plural noun. Among the given options (Son, sa, ses), "ses" is the only plural possessive adjective, agreeing with "frères".
   • The correct option is C.
   • $\boxed{\text{C. ses}}$

7. Mange du riz.

   • "Du riz" means "some rice". "Mange" is the third-person singular present tense of "manger" (to eat), or the informal singular imperative form ("Eat!"). It forms a grammatically correct and common phrase.
   • The correct option is B.
   • $\boxed{\text{B. mange}}$