水泵轴承每隔（）个月润滑一次，加入润滑脂过多，将导致轴承过热。
参考答案：6
用动词的适当形式填空。
1. I don't know if he (come) tomorrow. If he (come), I will tell you.
2. He (learn) two thousand English words by the end of last year.
3. When I saw her, she was busy (write) a letter.
4. Last night I (invite) to my teacher's home for dinner.
5. The workers are made (work) fourteen hours a day.
用兆欧表确认车体正线还是负线漏电？
