Answer:
quatrain; couplet
Step-by-step explanation:
A Shakespearean sonnet begins with a quatrain and ends with a couplet. This type of sonnet is comprised of three quatrains and a couplet. Moreover, they have a rhyme scheme of abab cdcd efef gg. This type of poem is also called English sonnet. Although it receives Shakespeare's name, many authors used this form before Shakespeare.