87． Because of the noise outside, Nancy had great difficulty __________________________(集中注意力在实验上)。
88． The manager never laughed; neither ___________________(她也从来没有发过脾气)
89． We look forward to _____________________________(被邀请出席开幕式)
90． It is suggested that the air conditioner _____________________________(要安装在窗户旁)。
91． The 16-year-old girl decided to travel abroad on her own despite ______________________________(她父母的强烈反对)。
参考答案：
87. (in) concentrating on the experiment/ focusing her attention on the experiment.
88. did she become angry/did she lose her temper before.
89. being invited to attend the opening ceremony.
90. (should) be fixed/installed by the window
91. the strong opposition of her parents/ her parents’ strong opposition.
解析：
87. 本题考查两个短语的用法，一个是have difficulty (in) doing sth， 该短语中，后面的动词要用现在分词形式。第二个短语是集中注意力，与此对应的有多个短语，如：focus/fix one’s attention on, concentrate on。翻译时需和前面短语的用法结合起来，把动词变成ing形式。
88. 本题考查neither的倒装用法，以及发脾气这个短语，发脾气可以说become angry，也可以用lose one’s temper。
89. 本题考查look forward to的用法，后面要跟名词或者动词的ing形式，而且要注意后边是被邀请所以要用被动语态。
90. 本题考查It is suggested that结构中主语从句中要用虚拟语气的用法，即should + 动词原形，should可以省略。
91. 本题考查despite的用法，注意despite是介词，后边应该跟名词或者名词短语。