压力式滤油机是利用滤油纸的毛细管吸收和粘附油中的水分和杂质，从而使油得到干燥和净化。
参考答案：对
There _____ lots of old houses here. But now we can see only tall buildings. [ ]
A. used to have
B. used to be
C. was used to be
D. was used to have
简述脑血管意外的概述
