zài kèshàng, lǎoshī chángcháng ràng wǒmen yòng zhōngwén wèn wèntí.

在 is a location marker meaning “at / in / on (a place or time frame)”.

• 在课上 literally = “during class / in class (time & place)”.
• Starting a sentence with 在 + place/time is a very common Chinese pattern:
  
  • 在家，我不说中文。 – At home, I don’t speak Chinese.
  • 在中国，他学了两年汉语。 – In China, he studied Chinese for two years.

You can drop 在 in very casual speech and just say 课上老师常常…, but:

• 在课上 sounds more standard and clear as a full locative phrase.
• For learners, using 在 is safer and more natural.

All three are similar but have slightly different flavors:

1. 课上

   • Literally “on/within the class (session)”.
   • Very common in everyday speech.
   • Focuses on the period while a particular class is going on.

2. 上课的时候

   • Literally “when (we are) having class”.
   • A bit more explicit about the time aspect (的时候 = when).
   • Feels slightly longer and more “sentence-like”, but very natural:
     
     • 上课的时候，老师常常让我们用中文问问题。

3. 在课堂上

   • Literally “in the classroom context / in class (as a learning setting)”.
   • Sounds a bit more formal or written than 在课上.

In practice, for this sentence, all of these are acceptable:

• 在课上，老师常常让我们用中文问问题。
• 上课的时候，老师常常让我们用中文问问题。
• 在课堂上，老师常常让我们用中文问问题。

The meaning is almost the same: “During class, the teacher often has us ask questions in Chinese.”

Chinese often puts time and place information near the start of the sentence, before the subject or right after it. All of these are grammatical:

1. 在课上，老师常常让我们用中文问问题。
2. 老师在课上常常让我们用中文问问题。

Nuances:

• Sentence‑initial 在课上 (version 1) slightly emphasizes the setting:
  
  • As for what happens during class… the teacher often has us…
• 老师在课上… (version 2) slightly emphasizes the teacher first, then when/where he/she does this.

Both are natural. Putting 在课上 at the very end, though, would sound odd:

• ✗ 老师常常让我们用中文问问题在课上。 (wrong)

Location/time phrases generally do not go at the very end after the object in Chinese.

让 is a causative verb. It means “to have someone do something / to make someone do something / to let someone do something” depending on context and tone.

Structure:

• 让 + person + verb phrase
• 老师让我们用中文问问题。
  
  • Literally: “The teacher lets/has us use Chinese to ask questions.”

In a classroom context, 让 usually implies:

• The teacher requires or asks students to do it as a rule or expectation.
• It’s not just “allowing”; it’s more like:
  
  • “The teacher has us…”
  • “The teacher asks us to…”

So functionally, you can understand it as “The teacher has us ask questions in Chinese (rather than another language).”

All three can appear in 老师 + (verb) + 我们 + do something, but they differ in tone and common usage:

1. 让

   • Neutral and very common.
   • Means “have / tell / require” someone to do something.
   • 老师常常让我们用中文问问题。
     
     • Very natural, standard classroom language.

2. 要

   • Stronger sense of “require / demand / need to”.
   • 老师要我们用中文问问题。
     
     • Feels more like a rule or requirement: “The teacher expects/insists that we ask questions in Chinese.”

3. 叫

   • In this pattern, often more colloquial.
   • Depending on region, can sound a bit more casual or spoken:
     
     • 老师叫我们用中文问问题。
   • Perfectly understandable, but 让 is safer and more standard in learner contexts.

For your sentence, 让 is the most natural choice.

用 means “to use (a tool/method/language)”.

In Chinese, when you talk about doing something in a certain language, you normally use 用 + language:

• 用中文说。 – Say it in Chinese.
• 用英文写。 – Write it in English.
• 用手机看新闻。 – Read the news with a phone.

So the pattern is:

• 用 + language + verb
• 用中文问问题。 – Ask questions in Chinese.

老师让我们中文问问题 is ungrammatical because 中文 wouldn’t have the needed verb 用 to connect it as a tool/method to 问. You need 用 to show that Chinese is the medium used for asking.

In Chinese, 问问题 is a very natural collocation and not considered awkwardly redundant.

• 问 by itself means “to ask”, but doesn’t specify what.
• 问题 means “question(s), problem(s)”.

You have options:

1. 问问题 – to ask questions (general)
   
   • 老师让我们用中文问问题。
2. 问一个问题 – to ask a question (one)
   
   • 老师让我们用中文问一个问题。
3. 问他 – to ask him (no explicit “question” word)
   
   • 你有不懂的地方，可以问他。

In English, “ask a question” also sounds a bit redundant if you think about it literally, but it’s completely normal. 问问题 works the same way in Chinese.

Just saying 老师让我们用中文问 feels incomplete; native speakers expect an object like 问题 or a person (他/老师).

They overlap but aren’t identical:

1. 中文 (zhōngwén)

   • Literally: “Chinese (written) language”.
   • In modern usage: the Chinese language in general, spoken or written.
   • Very common in everyday speech, especially from learners or in international contexts.
   • Your sentence with 用中文问问题 is perfectly natural.

2. 汉语 (hànyǔ)

   • Literally: “the language of the Han people”.
   • Often used in linguistics, education, and more formal descriptions.
   • Textbook titles: 汉语课本, 汉语水平考试 (HSK).
   • You could also say:
     
     • 老师常常让我们用汉语问问题。 (fine, a little more “textbook-ish”)

3. 普通话 (pǔtōnghuà)

   • Literally: “common speech”, i.e. Standard Mandarin as defined by the PRC.
   • Refers specifically to the standard spoken variety, not Chinese in general.
   • You’d use it when contrasting with dialects:
     
     • 在上海，我们上课只说普通话，不说上海话。

For your sentence, 中文 is the most neutral, most commonly used choice.

Whether you need a measure word depends on how specific you are being:

1. General / unspecific “questions” → no measure word

   • 问问题 – ask questions (in general)
   • 有问题吗？ – Are there (any) questions?

2. Specific number or amount → need a measure word

   • 问一个问题 – ask one question
   • 问几个问题 – ask a few questions
   • 有三个问题要问老师。 – have three questions to ask the teacher

In your sentence:

• 让我们用中文问问题 = “have us ask questions in Chinese” (no particular number).
• If the teacher said “Each of you must ask one question in Chinese,” you’d say:
  
  • 老师让我们每个人用中文问一个问题。

In Chinese:

• Nouns usually do not change form for singular vs. plural.
• 们 is only used in a limited way:
  
  1. After personal pronouns:
     
     • 我 → 我们
     • 你 → 你们
     • 他 → 他们
  2. After some human nouns to explicitly indicate a group (but not always necessary):
     
     • 老师们, 同学们, 孩子们, etc.

For 老师 here:

• 老师常常让我们… can mean “the teacher” (one) or “teachers (in general)”, depending on context.
• Chinese often leaves number implicit if it isn’t important.

If you really want to emphasize multiple teachers as a group, you can say:

• 老师们常常让我们用中文问问题。

But in a typical sentence like this, 老师 without 们 is completely normal and doesn’t sound singularly restrictive the way English “teacher” does.

常常 (often) is an adverb of frequency. In Chinese, adverbs like this usually go:

• before the main verb they modify.

Common placements in your sentence:

1. 老师常常让我们用中文问问题。

   • Most natural. “The teacher often has us ask questions in Chinese.”

2. 老师让我们常常用中文问问题。

   • Now 常常 modifies 用, suggesting “The teacher has us frequently use Chinese to ask questions.”
   • Grammatically OK, but slightly different emphasis (frequency of using Chinese itself).

3. 在课上，老师常常让我们用中文问问题。

   • Same logic, with 常常 before 让.

You normally would not say:

• ✗ 常常老师让我们用中文问问题。 (sounds wrong – adverb before subject)

So best patterns are:

• 在课上，老师常常让我们…
• 老师在课上常常让我们…

No. In this sentence, 我们 is required because 让 needs an explicit person who is being made/asked/allowed to do something.

Structure:

• 让 + [who] + [do what]
• 老师让我们用中文问问题。
  
  • “The teacher has us use Chinese to ask questions.”

If you remove 我们, you get:

• ✗ 老师常常让用中文问问题。

This is ungrammatical because:

• 让 is left without a person as its object.
• Native speakers will feel something is missing.

You can omit 我们 if it’s understood from context and you change the structure, e.g.:

• A: 你们在课上说什么语言？
  B: 老师常常让（我们）用中文。

Here, you might drop 我们 in casual speech because it’s obvious who is being talked about. But in a full standalone sentence like yours, keep 我们.

It is both natural and very typical textbook‑style — which is a good thing.

• Grammar: Completely correct.
• Word choice: Very standard, no weirdness.
• Register: Neutral; appropriate for spoken and written usage.

A native speaker could easily say this in real life in many contexts, for example:

• Describing a class to a friend:
  
  • 在课上，老师常常让我们用中文问问题，还让我们分组讨论。

So it’s not “unnatural” at all; it just happens to be the kind of sentence that also works well in a beginner/intermediate textbook because the structure is clear and representative of real usage.