1、“be of+抽象名词”,这时的of短语相当于这个名词的同根形容词,作为
表语表示主语的性质或特征。of的意思是“具有、具备”等.
of importance=important
2、“be of+
集合名词或其它类型的名词”,相当于belong to或have。of表示归属关系或“有”的意思。
The army and the people are of one family.=The army and the people belong to one family.
3、“be of+物质名词”表示主语是“用某种材料构成或制作的”,相当于be made of或be built of。
Our building was of bricks.=Our building was built of bricks.