87. David turned away and walked quickly down the street, ________________完全无视他的存在。

　　88. it is man’s intellect__________________才使他区别去其他高等动物

　　89. I read the book last week, but now it is _______________哪儿也找不到了。

　　90. Hardly had John finished his introductory remark _________他就被听众打断了。

　　91. If the reaction were to take place_______________巨大的能量就会被释放出来

【责任编辑：青枫】