Can I put `昨天` before `为什么`?

Question

Below is a correct sentence.

你为什么昨天没有跟我讲?

Can I put 昨天 before 为什么 as following?

你昨天为什么没有跟我讲?

Answer 1

Actually, both are fine in speaking (I interchangeably use both with my teacher), but if you want to be more correct, especially for writing purpose, I suggest to put the time specifier before the 为什么, because in mandarin the sentence structure usually prioritize the time and place after the subject (and based on my experience, my teacher always correct me every time I put place and time specifier in the later section of a sentence). Here you can check both of these links in the Expressing "Why" with 为什么 (wèishénme) section:

as you can see, in the example, the time specifier 早上 is written before the 为什么.

https://resources.allsetlearning.com/chinese/grammar/Placement_of_question_words https://vividchinese.com/sentence-structure/

Answer 2

In general, the two sentences are the same. But things can be more interesting than that because the topic can be for the time 昨天 or for the action 不说. For example,

(1) 你昨天为什么没有来公司上班呢？（你是生病了，还是去见女朋友了？）

Why didn’t you come to work yesterday? (There might be a reason, either got sick or went to meet your GF?)

(2) 你为什么昨天不来？（我告诉过你了，我今天没时间。）

You really should have come yesterday but you didn’t. (Because I told you that I am not available today.)

(3） 你为什么昨天没来，今天还不来？（我不关心什么原因，但是你不能连续两天不来。）

You didn’t come yesterday, nor today. Why is that? ( I am not asking for excuses, but you just can’t do that.)

Answer 3

There are more than two acceptable possibilities:

1. 你为什么昨天没有跟我讲?
2. 你昨天为什么没有跟我讲?
3. 昨天你为什么没有跟我讲?
4. 为什么你昨天没有跟我讲？

Hard to explain!