下列哪一项不宜用来同时承受径向和轴向载荷?( )
D
圆柱滚子轴承只能用来承受径向载荷，不能承受轴向载荷。
对带有混合水泵的直接连接热水供暖系统，若网路的设计供回水温度130/70℃，供暖用户的设计供回水温度95/70℃，承担供暖设计热负荷的网路流量为100t/h，则从二级网路抽引的回水量为()。
为降低严寒地区全年供暖空调能耗，下列关于玻璃性能的说法，哪几项是错误的?（）
On no account ____ ever leave the baby at home alone.
When the idea of winning in sports is carried to excess, ____competition can turn into disorder and violence.
I ’ve nev er been out of China___________. What about you?
How long have you____?
People in some areas don’t have to pay for their ______.
I still remember the days ____ we studied together.
He didn't know which room ____.
We expect Mr. White will ____Class One when Miss Jane retires.
The doctor ____ is leaving for Africa next month.
He paid the boy $10 for washing ten windows,most of ____ hadn't been cleaned for at least a year.