Final answer:
The correctly completed sentence is 'Yo sé un poco', using the verb 'saber' in the first person singular present tense.
Step-by-step explanation:
In the provided sentence, the correct form of the verb 'saber' which means 'to know' in Spanish, conjugated in first person singular present tense is 'sé'. Hence, the fully completed sentence would read 'Yo sé un poco', which translates to 'I know a little' in English.
Learn more about Verb Conjugation