矩形具有而平行四边形不一定具有的性质是( )
A.对角相等
B.对边相等
C.对角线相等
D.对角线互相平分
矩形的对角线相等,而平行四边形的对角线不一定相等.故选C.
Every year in the U. S. , colleges and graduate schools continue to highly () trained people to compete for jobs that are not there. As a result, graduates cannot enter the professions for which they were trained.
A. turn out
B. work out
C. make out
D. bring out
关于通风系统类型的描述,下面哪些描述是正确的()
A.默认模板中一般自带的是送风、回风和排风三个
B.可以通过复制已有系统类型的方式来新建新的系统类型
C.可以删除模板中自带的系统类型,直至完全清空
D.新建的系统类型可以保存在自定义模板中