题目内容：
2、 In a piston pump, liquid is drawn through an inlet check valve into the cylinder by the withdrawal of a piston and then is forced out through a discharge check valve on the return stroke.
参考答案：
选择题：2、 In a piston pump, liquid is drawn through an in
- 题目分类：乐山师范学院专业英语
- 题目类型：选择题
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