时时, 一时, 早晚: constantly, for a moment, sooner or later
【六08】时间副词 / adverbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Three time adverbs of a more formal register. 时时: "constantly, at every moment", the written 常常 with a sense of continuity (老师时时关注着我们的学习). 一时: "for the moment, momentarily", for a lapse of memory, an impulse, a passing mood (一时想不起来, 一时冲动). 早晚: "sooner or later", for what is bound to happen (他早晚会知道真相的).
Watch the false friends. 暂时 ("temporarily") names a temporary arrangement, whereas 一时 names a very brief state. 早晚 looks ahead and goes with 会 or 要, so it never takes a completed-action 了. The noun 早晚 ("morning and evening", 早晚各吃一次) exists too.
To alternate two states, speech prefers 一会儿……一会儿……; in writing you will meet 一时……一时…… or 时而……时而……, mostly in narration.
Examples
他早晚会知道真相的。
Tā zǎowǎn huì zhīdào zhēnxiàng de.Sooner or later he will find out the truth.
我一时想不起他的名字了。
Wǒ yìshí xiǎng bu qǐ tā de míngzi le.For the moment I can't recall his name.
老师时时关注着我们的学习。
Lǎoshī shíshí guānzhù zhe wǒmen de xuéxí.The teacher keeps a constant eye on our studies.
他一时冲动，说了不该说的话。
Tā yìshí chōngdòng, shuō le bù gāi shuō de huà.In a moment of impulse he said what he should not have said.
别担心，这样的机会早晚还会再来。
Bié dānxīn, zhèyàng de jīhuì zǎowǎn hái huì zài lái.Don't worry, a chance like this will come again sooner or later.
她时时提醒自己，不能骄傲。
Tā shíshí tíxǐng zìjǐ, bù néng jiāoào.She constantly reminds herself not to be proud.
Common mistakes
✗ 我一时住在北京。 → ✓ 我暂时住在北京。 (一时 is a brief moment or mood, not a temporary arrangement).
✗ 昨天他早晚知道了。 → ✓ 他早晚会知道的。 (早晚 looks ahead: no past fact, no 了).