| 51. | a run off primary |
| （第一次投票后在票数最高的两个候选人之间进行的）第二次预选
|
| 52. | a primary cause |
| 首要原因
|
| 53. | primary [fundamental, simple] colours |
| 原色（指红、黄、蓝等）
|
| 54. | primary [secondary] clock |
| 母[子]钟
|
| 55. | primary [secondary] coil |
| 初级[次级]线圈
|
| 56. | a matter of primary consideration |
| 头等要事
|
| 57. | distinguish colours into primary and secondary |
| 将颜色分为原色与调和色
|
| 58. | an elementary [a primary ] |
| 小学
|
| 59. | the primary sense of the word |
| 这个词的原义
|
| 60. | primary [original] sources |
| 最初的出处
|