Perfect Tense

question 6

Multiple Choice

Perfect tense

• A) indicates that action is completed and is formed by using a helping verb along with the past tense form of the main verb ( have learned ).
• B) indicates that an action is ongoing and uses the - ing form of the main verb ( was learning ).
• C) cannot be used with irregular verbs.
• D) can be used only with the past tense of verbs.

---

Definitions:

Genetic Variation

The differences in DNA sequences among individuals within a population, leading to diversity in traits.

Genotypic Frequencies

The proportion of different genotypes in a population, which can change over time due to evolutionary processes.

Nonevolving Population

A theoretical population in which allele frequencies do not change over time, effectively not undergoing evolution.

Speciation

Origin of new species due to the evolutionary process of descent with modification.