第三节 语法填空（共10小题; 每小题1.5分，满分15分）
阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空，并将答案填写在答题卷标号为46-55的相应位置上。
Not all memories are sweet. Some people spend all 46 lives trying to forget bad experiences. Violence and traffic accidents can leave bad memories on people’s minds.
Now American researchers are developing a pill, 47 will help people forget bad memories. The pill is planned to be taken immediately after a 48 (frighten) experience. They hope it might reduce, or possibly erase, the effect of painful memories.
