1.There ___ nothing to do in the factory, workers went home.
C.to have been
2.She handled the instrument with care for fear that it ___ damaged.
3.Algonkian-speaking native Americans greeted the Pilgrims ___ settled on the eastern shores of what is now New Zealand.
4.___ the United States consists of many different immigrant groups, many sociologists believe there is a distinct national character.
A.In spite of
5.___ that the most powerful microscopes cannot detect them.
A.So small these particles are
B.So small are these particles
C.Such these particles are small
D.These particles are small so
2.[C]【解析】for fear that意为“恐怕”，从句必须用虚拟语气should do表示。
4.[C]【解析】even though表示“即使，尽管”，引导让步状语从句；in spite of和despite为介词，后面接名词或名词性从句。