As I'm sure my English-speaking readers would agree, the agent marker "-er" is tough for Chinese learners. We use it all the time in English (3 times in the previous sentence) but it's not so readily available in Chinese.

Example 1: Tennis Player

Imagine I see a girl walking down the street with a tennis racket in her hand. I want to dāshàn 搭讪 (not to be confused with you-know-who). In English, I'd say something like:

"Nice racket you've got there. So, are you a tennis player?"

How would we translate that second sentence into Chinese? Well, looking at "reporter" (jìzhě 记者) and "scholar" (xuézhě 学者) we see that you just add "-zhě" 者 to the end of a verb and you've suddenly got a noun meaning "someone who VERBs." Unfortunately, even though the grammar is technically correct for a literal translation, the word dǎzhě 打者 doesn't exist, so this is impossible:

Wrong:Nǐ shì wǎngqiú dǎzhě ma? 你是网球打者吗? = Are you a tennis player? [you are tennis play-er {p}]So what should we say? The other agent markers are out because you can't add them to "dǎ" 打 either:

• -jiā 家 = -er (like in "huàjiā" 画家 = painter)
• -yuán 员 = -er (like in "yǎnyuán" 演员 = actor / performer)

These words do not exist is Chinese:

Wrong:Nǐ shì wǎngqiú dǎjiā ma? 你是网球打家吗?Nǐ shì wǎngqiú dǎyuán ma? 你是网球打员吗? You could add yuán 员 to "tennis," but that sounds too professional:

Nǐ shì wǎngqiúyuán ma? 你是网球员吗? = Are you a (professional) tennis player?

That's not really my question. I just want to know if she plays tennis.So I suggested to my informants the trusty "shì...de" 是...的 construction:

Nǐ shì dǎ wǎngqiú de ma? 你是打网球的吗? = Are you a tennis player? [you are play tennis {p} {p}]

They said it's ok, but sounds strange. It turns out what most Chinese people would say is simply:

Nǐ huì dǎ wǎngqiú ma? 你会打网球吗? = Do you know how to play tennis?

OR better yet:

Nǐ jīngcháng dǎ wǎngqiú ma? 你经常打网球吗? = Do you often play tennis?

I know, I know, I know. We don't want to talk about how often she plays, but that's the way Chinese people would ask our original question, "Are you a tennis player?" or "Do you play tennis?" Apparently, adding the "jīngcháng" 经常 in there is better (or at least more dìdao 地道) than just saying: "Nǐ dǎ wǎngqiú ma?" 你打网球吗?Lesson 1 = If you can leave out the agent marker and just ask a simple "Do you often VERB?" question, that's probably best.

Example 2: Drummer

But sometimes that's really not what I want to know. Imagine I'm at a rock show and I meet a band of 4 guys before their set. I want to know who is the drummer in the band. Now, I could just ask each of them:

Nǐ huì dǎ gǔ ma? 你会打鼓吗? = Do you know how to play the drums?

But there's always that chance, especially because everyone knows how to hit stuff, that they'll ALL say, "Yes." They might even hit them pretty often, which renders the "jīngcháng" 经常 construction useless. I really just want to ask about the drummer! Enter: "hand."

Nǐ shì gǔshǒu ma? 你是鼓手吗? = Are you the drummer? [you are drum-hand {p}]

"Hand" works as the agent marker for most (all?) instrumentalists (jítāshǒu 吉他手 = guitarist) and in some other situations as well:

• xuǎnshǒu 选手 = competitor / contestant [choose hand]
• shuǐshǒu 水手 = sailor [water hand]
• qiāngshǒu 枪手 = gunner [gun hand]
• duìshǒu 对手 = opponent [opposite hand]

Summary

I'm always looking for some sort of guīlǜ 规律 to guide me when thinking about these things and here's what I've got so far (although it's not even close to perfect):

1. If it's the formal name of an actual job (reporter, scholar, actor, tennis player, etc.) look for some sort of formal word that may use any of the following: "-zhě" 者, "-jiā" 家, or "-yuán" 员 to create the job title.
2. If it's less formal or more of a temporary or amateur position (drummer in a band, competitor) look to add "-shǒu" 手 after the main noun involved (sailor and gunner are exceptions I guess, as is ).
3. If you just want to talk about a hobby, just ask "Do you often VERB?"

As an example, if I want to create a formal book club dedicated to reading the collected works of Lǔ Xùn 鲁迅, I'd say:

Lǔ Xùn de dúzhě 鲁迅的读者 = readers of Lu Xun

(One student told me that authors often thank the "dúzhě" 读者 at the end of a book.)

But after that tennis racket girl shuts me down and I want to change tactics and ask if she's an avid reader, I should say:

Nà, nǐ jīngcháng kàn shū ma? 那,你经常看书吗? = So, do you often read books?

She'll probably think I'm a player or a loser and just walk away.