C. le 了is used to ask about what someone did.The question uses the modal particlele 了, which is the sentence-end le 了, butthe answer must use the verb-suffixle 了, the aspect particle, and the object must be quantified in terms of quantity or duration. If the verb is qù 去, it usually takes the suffix le 了 and a verbal measure word yí tàng 一趟 (a trip to) before taking the object which indicates a place.

    1. Zuótiān wǎnshang nǐ dōu gàn shénme le?
      昨天晚上你都干什么了？
      What did you do last night?


    2. Xiě-le yì fēng xìn, kan-le yì huǐr diànshì, hái qu-le yí tàng túshūguǎn.
      写了一封信，看了一会儿电视，还去了一趟图书馆。
      I wrote a letter, watched a little TV and also went to the library.

    Thedōu都used in the question is to show expectation of a list of events.


    1. Shàng gè zhōumò nǐ dōu mǎi shénme le?
      上个周末你都买什么了？
      What did you buy last weekend?


    2. Méi mǎi shénme. Jiù mǎi-le yì běn xiǎoshuō.
      没买什么。就买了一本小说。
      I didn't buy much. I only bought a novel.


    1. Wǔfàn nǐ dōu chī shénme le?
      午饭你都吃什么了？
      What did you eat at lunch?


    2. Wǒ chī-le bàn tiáo yú hé yì diǎnr qīngcài.
      我吃了半条鱼和一点儿青菜。
      I ate half a fish and some vegetables.

The verb in this type of what-question can be any action verb that takes an object. The important thing is that this type of question asks for very specific information, so the answer must use verb-suffix le 了 and the object must be quantified or modified. The question, however, uses the sentence-end modal particle le 了. “The more specific and delimited the action is made by reference to particular context, the greater the need for this verb-suffix–le, to the degree that it is obligatory where precision is given to the object or complement by quantifying it.” (P.C. T 'ung and D. E. Pollard: 1982, p. 142)