Cultural Insight:
In Chinese culture, numbers not only have mathematical meaning but also carry symbolic meanings of good and bad fortune. The most famous are "8" and "4." Because the pronunciation of "8" (bā) is close to "发" (fā, meaning to make a fortune, to prosper), 8 is considered the luckiest number. People will spend a lot of money to have phone numbers or license plates with 8s. Conversely, the pronunciation of "4" (sì) is very close to "死" (sǐ, meaning death), so it is considered unlucky. Many hospitals avoid using 4 in floor and room numbers.

Useful Sentences:

1. 我的幸运数字是8。 - My lucky number is 8.

2. 这个号码有很多8。 - This number has many 8s.

3. 我不喜欢数字4。 - I don't like the number 4.

4. 这是为什么？ - Why is that?

Grammar Corner: The Conjunction "因为...所以... (yīnwèi... suǒyǐ...)"
This structure is used to express a causal relationship, equivalent to "Because... therefore...".

• Structure: 因为 + Reason， 所以 + Result

• Examples:

• 因为下雨了，所以我不能去公园。 - Because it's raining, therefore I can't go to the park.

• 因为"8"和"发"声音差不多，所以8是个幸运数字。 - Because "8" and "发" sound similar, therefore 8 is a lucky number.

Exercise:
Use "因为...所以..." to connect the sentences.
他很忙。/ 他没来吃饭。
→ 因为他很忙，所以他没来吃饭。