What is the market value (No.1)
The classic“是…的” " shì....de " construction.
This classic pattern is the one for emphasizing certain details about events in the past. It's often used to ask pointed questions about past events, and then to answer those questions. Usually, the situation is already established, and the speakers are trying to get more specific clarification, such as when, where, and how the action took place. When in this case, the phrase that follows the "是" is the part of the situation that is being emphasized.
It is also important to know that you can't use "了" in this sentence. "了" only tells you that the action is completed, not any of the other details that this construction is looking for. Since it is already understood that the action has taken place, the "了" is unnecessary.
nĭ shì shén me shí hou kāi shĭ xué zhōng wén de ？
When did you start to learn Chinese?
nĭ shì zĕn me qù shàng bān de ？
How do you go to work?
就 jiù emphasizes earliness. Structure: Subj. +Time+就 jiù +Verb+ Obj.
tā hái méi shuō ， wŏ jiù zhī dào le 。
I knew it, even before he said it.
nĭ hái méi rèn shi tā yĭ qián ， wŏ jiù rèn shi tā le。
I knew him even before you knew him.
Omission of measure words. We sometimes omit the measure words when talking about people in spoken Chinese.
wŏ yŏu yì gē men 。
I have a good mate.