一度 vs 一时 (at one time vs for the moment)

A past phase, a passing moment

• Both touch "for a time" — but differ.
• for a time一度yí dù = at one time / once (a past period that has passed).
• a period of time一时yī shí = momentarily / for the moment (a brief, current instant).

for a time一度yí dù = at one time (a past phase)

• this这zhè首歌shǒu gēfor a time一度yí dùvery很hěn(of a contagious disease…流行liú xíng = "this song was once very popular."

this这zhè(measure word)首shǒusong歌gēat one time一度yí dùvery很hěnpopular流行liú xíng。

• for a time一度yí dùvery很hěn(of a contagious disease…流行liú xíng = "was once very popular."

a period of time一时yī shí = for the moment

• I / me我wǒa period of time一时yī shí想不起来xiǎng bù qǐ lái = "I can't recall it for the moment."

I我wǒfor the moment一时yì shícan't recall想不起来xiǎng bù qǐ lái。

• a period of time一时yī shí想不起来xiǎng bù qǐ lái = "can't recall (it) right now."

Recap

Read the full reference: HSK 6 grammar — Comparing similar adverbs.