填空题 Questions 9-11
Complete the sentences below.
Write NO MORE THAN THREE WORDS for each answer.

填空题 Researchers have started to pay more attention to ______ rather than just focus on brain mechanisms of some negative mental behaviors.

填空题 Although ______ may be ascended to some degree, the immunity could be strengthened by laughter.

填空题 When people heard a funny joke, he may substantially awake the field of ______ .