离心式鼓风机的密封间隙一般是多少？
参考答案：
滑动轴承箱内密封在安装前一般为0.18～0.25mm；机壳内密封在安装前一般为0.20～0.40mm。
My friend Li Lei likes salad, but I don't like ______at all. [ ]
A. it
B. them
C. its
D. they
