答案与解析：

　　87. Thanks for/Due to series of new inventions

　　解析：考点是词组“多亏，由于”。

　　88. I feel/get tired more easily than before

　　解析：考点是比较级more … than.

　　89. no matter what sacrifice I am going to make/ whatever sacrifice I will make/ no matter how much I would sacrifice

　　解析：考点是状语从句。

　　90. it/ the former is more convenient and timesaving

　　解析：考点是比较级more, 词汇。

　　91. is measured by how much they can borrow

　　解析：考点是被动语态、宾语从句。