פועל + 了 + 又 + פועל (שוב ושוב)

A message needs a second careful look

• this这zhè封信fēng xìnI / me我wǒlook看kàn(completed / change)了leagain又yòulook看kàn。 The same action is repeated: the speaker looked at the letter again.
• The expression highlights repetition. It does not state an exact count or prove that the speaker understood the letter.

Repeat the same verb around (completed / change)了leagain又yòu

• Use look看kàn(completed / change)了leagain又yòulook看kàn、want / think / miss想xiǎng(completed / change)了leagain又yòuwant / think / miss想xiǎng or to ask问wèn(completed / change)了leagain又yòuto ask问wèn for the repeated-action pattern. again又yòu introduces another occurrence of the action.
• The (completed / change)了le here is not a universal past-tense ending. The full sentence and time expression place the account in time.

he他tālook看kàn了leagain又yòulook看kàn。

Contrast repetition with different actions

• I / me我wǒlook看kàn(completed / change)了leagain又yòulook看kàn repeats looking. I / me我wǒlook看kàn(completed / change)了lecharacter文字wén zì，again又yòuto listen to听tīng(completed / change)了leto record (sound)录音lù yīn sequences reading text and listening to audio.
• The second account can be grammatical; it simply does not use the same-verb repetition pattern. A different construction is not automatically broken.

Repetition does not give an exact count

• he他tāto ask问wèn(completed / change)了leagain又yòuto ask问wèn reports repeated asking. he他tāto ask问wèn(completed / change)了lethree times三次sān cì explicitly counts three questions or asking occasions in the context.
• Use the stated count when accuracy matters. Do not infer exactly two or exactly three from the repeated-verb pattern.

Read the following outcome

• he他tāwant / think / miss想xiǎng(completed / change)了leagain又yòuwant / think / miss想xiǎng，or / still还是hái shìto refuse拒绝jù jué(completed / change)了le。 Repeated consideration ends in refusal in this account.
• Repeated thought can lead to different decisions. The final clause supplies the decision rather than the repeated-action form itself.

Keep action, time and outcome separate

• yesterday evening昨晚zuó wǎnI / me我wǒlook看kàn(completed / change)了leagain又yòulook看kàn，finally终于zhōng yúto notice发现fā xiàn(completed / change)了lemistaken错误cuò wù supplies a time, repeated action and eventual discovery. Each part contributes its own information.
• In a new example, identify which verb repeats, what time is stated and what outcome follows. Avoid adding a count or successful result that is absent.

Read the full reference: HSK 5 grammar — Adverbs.