题目

Not all memories are sweet. Some people spend all 36 lives trying to forget bad experiences. Now American researchers are developing a pill,     37     will help people forget bad memories. The pill is planned to be taken immediately after a 38                                                                               (frighten) experience. They hope it might reduce, or possibly erase, the effect of painful memories. However, the new research has caused a lot of argument. Supporters say bad memories may ru 49+39=()( ) 1-35=(  )(  ) 710+310-23=(  )(  )．