问题
单项选择题
液压支架乳化液泵常用的柱塞密封为密封圈和（）形密封圈。
A.O
B.矩
C.三角
答案
参考答案：A
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液压支架乳化液泵常用的柱塞密封为密封圈和（）形密封圈。
A.O
B.矩
C.三角
参考答案：A
| 选择方框里的词或词组并用其恰当形式完成句子，其中有两项是多余的。 | |
2. I __________ with my friends at the mall last Sunday. 3. He likes __________ his friend's homes on weekends. 4. Her father usually __________ as Father Christmas on Christmas Eve. 5. It's not polite to _________ while you are eating. |