(–le了) + durational complement + (le了)
Stating how long the object has been being dealt with as a result of the action or how long one anticipates it will be being dealt with.
13.1 Tāmen bǎ zhèi ge
wǔ nián duō.
They studied this problem for over five years.
13.2 Wǒ yǐjīng bǎ ròu kǎo-le wǔ fēnzhōng le. Zài kǎo jiù gāi kǎohú le.
I have grilled the meat for five minutes so far. If I continue, I will burn it.
13.3 Bǎ shuǐ rè
Heat the water for five minutes.
13.4 Wǒ bǎ miàntiáo zhǔ-le yì huǐr, ránhòu cái wàng
lǐ fàng cài.
I boiled the noodles for a little while before putting vegetables in it.
Note: Only verbs that imply certain forms of processing, such as shāo烧(to heat), kǎo烤(to bake/to roast), rè热(to heat). zhǔ煮(to boil), lěngquè 冷却(to cool off), can take a durational complement in bǎ sentences. This is why the following example is ungrammatical.
Wǒ bǎ shū kàn-le sān ge xiǎoshí.
(I read the book for three hours.)
If the speaker intends to state how long the action kàn看‘reading’ lasted, the bǎ construction should not be used.
13B. Wǒ kàn shū kàn-le
sān gè xiǎoshí. (Grammatical)
I read the book for three hours.