液压牵引采煤机常用液压马达的形式有哪几种?
参考答案:
液压牵引采煤机常用液压马达的形式有斜轴轴向柱塞式、通轴轴向柱塞式、摆线式、单作用径向活塞式、叶片式和内曲线径向柱塞式。
The British government often says that providing children with ______ to the information superhighway
is of great importance. [ ]
A. prevention
B. protection
C. allowance
D. access
陪补离子与土壤胶粒之间吸附力量越大,则越能提高该种养分离子的有效度。