時常，有時，不時
from time to time是 time 的常見短語，是壹個表示頻度的介詞短語，其頻度和 at times， sometimes ，now and then是同意表達，都表示“有時”的意思。
from time to time=sometimes=at times=now and then
頻度比較
always>usually>often>from time to time>occasionally>seldom>hardly
例句：
1. She sat silently,flinging the odd word into the conversation from time to time.
她靜靜地坐著聽談話，不時插進壹兩句。
2. He threw in a word or two from time to time.
他時不時冒出壹兩句話。