单词：not once or twice
adj. 屡次(常常)
not once or twice的用法和样例：
例句
用作形容词(adj.)
- Frequent failures did not affect his morale.屡次失败都没有使他泄气。
- From time to time, scientists have speculated that the proton and electron charges might not be exactly equal in magnitude.屡次地，科学家们推究质子与电子的电荷大小可能不恰好相等。