牵引时的列车所能达到的最高速度由()最大定子频率所决定的。
参考答案:牵引电机
Think and write. 用动词的适当形式填空。
1. Tom, (not walk) on the grass.
2. The geese (catch) the fish now.
3. My grandma (watch) TV every day.
4. His parents (go) to Beijing last week.
5. We like (play) football after school.
6. Look! The girls (sing) in the hall.
7. (be) there any money in your hand?
8. Lily (have) got a new dress, I (have) got one, too.
混合料加水的目的是为了防尘。