流化床清洗具有传热均匀、不会引起清洗物变形的特点。
参考答案：对
介词填空。
l. That was an important date ________ which we set up our own business.
2. This was a difficult period ________ which we went through many sufferings.
3. He returned to the village ________ which he spent his happy childhood.
4. Do you know the reason ________ which he is absent?
5. Is this the car _______ which you paid a high price?
钢管常用带压封堵设备有囊式和桶式两种，以桶式为主，桶式封堵设备应用在钢管（）到DN720的各种管径上。
A、DN50
B、DN80
C、DN100
D、DN150
