Part 4. Verbs
rections: Fill in the space with the correct form of the verb in parenthesis: simple present, simple past
gerund, infinitive, or base verb form.
(3.
_(1. study) sleep is Matt Walker's career goal. Over the past several years,
Walker and his research team
(2. begin) and
complete) a series of research experiments to see how sleep and lack of it can
(4. affect) the human body. In these experiments, they _
_(5. find/past) that
sleep affects reproduction, memory, and even DNA. The scientists
(6. learn/past) that sleep deprivation can severely and negatively affect the human immune
response. Walker began by.
(7. speak) about human hormones important
for reproduction. He
(8. claim) that men who sleep only four to five hours
a night have the hormones of someone that is an entire decade older. He
(9. negative/think) that people can "catch up on sleep. He talks about _
(10. learn) strategies to sleep better. He says people need
(11. have)
consistency in their sleep routine and a cold room.