橡胶软管分为（）（）软管。
参考答案：高压、低压
He made ________ known to his friends that he didn’t want to enter politics.
A．that
B．it
C．himself
D．him
凝结水常用的过滤形式有（）。
A、覆盖过滤
B、磁力过滤
C、微孔过滤
D、粒料过滤
