Answer:
The correct use of the words in the parentheses is:
1. Martín trabaja en una escuela <u>pequeña</u>.
2. Las dos hermanas son <u>morenas</u>.
3. Las tías <u>francesas</u> de Ana María llegan a las seis.
4. La Universidad de Toronto y McGill son dos universidades <u>canadienses</u>.
5. La tarea de la clase de física es <u>difícil</u>.
6. La profesora explica los conceptos <u>importantes</u>.
7. Mi abuela <u>inglesa</u> se llama Eleanor.
8. ¿Cuál es la capital , San Juan o San José?
- <u>San José es la capital de Costa Rica.</u>
Explanation:
You must know that <u>the adjectives could be plurals and express the gender of the noun (male or female) in Spanish</u>, by this reason, an adjective could have four forms: female singular, male singular, female plural, and male plural, then, you must see the next reasons:
1. The noun "una escuela" is female singular, by this, the correct form of the "pequeño" is "pequeña" with the vowel "<em>a"</em> (the vowel would be<em> "o"</em> for the male noun) and without a consonant <em>"s"</em>.
2. "Hermanas" is a noun female and plural, that's the reason why the correct form is "morenas" with vowel <em>"a"</em> (that is used for female) and <em>"s"</em> (used for the plurals).
3. "Las tías" is a noun female and plural, by this reason the correct form is "francesas" (with the vowel a and s).
4. How "canadiense" hasn't gender, just must use the consonant "s" to express that "las universidades" are in plural form.
5. "Difícil" has not to gender, and how "la tarea" is a singular noun, the correct form is "difícil".
6. "Importante" is another adjective without gender, then you must see the noun "conceptos" that is in plural form, for this reason the correct form of the adjective is "importantes".
7. "Mi abuela" is a singular and female noun, for this reason, the correct form of the adjective "inglés" is "inglesa".
How can you see, <u><em>regularly the female form has the vowel </em></u><u><em>"a" </em></u><u><em>in the ending, the male form the vowel </em></u><u><em>"o"</em></u><u><em>, and the plural forms finish in </em></u><u><em>"s"</em></u>.