Expressing "even more" with "geng" or "hai"
When used in a comparison, 更 (gèng) or 还 (hái) expresses an even higher degree of the adjective.
For example, New York is America's biggest city with a population of more than 8 million. Shanghai is China's biggest city, with a population of more than 20 million. “上海比纽约人口更/还多” emphasizes that New York already has a high population (already known situation), but Shanghai's population is obviously higher.
Noun 1 + 比 + Noun 2 + 更 / 还 + Adj.
- 我 妹妹 比 我 更 瘦 。My younger sister is even skinnier than me.
- 我 的 猫 比 我 的 狗 更 淘气 。My cat is even more naughty than my dog.
- 有时候 动物 比 人类 更 聪明 。Sometimes animals are even smarter than human beings.
- 大城市 的 工作 机会 比 我老家 更 多 。There are more job opportunities in big cities than in my hometown.
- 他 比 姚明 还 高 。He is even taller than Yao Ming.
- 昨天 38 度 ，今天 比 昨天还 热 。It was 38 degrees yesterday, and it's even hotter today.
- 这个 老外 的 汉语 说 得 比 中国人 还 地道 。This foreigner speaks even more authentic Chinese than native speakers do.
还 has a more intense tone, and it usually carries a tone of surprise and skepticism. Therefore, using the form of a rhetorical question with 还 can be understood as "how can it be?" Note that 更 cannot be used in an interrogative tone.
- 你 比 老板 还 忙 ？You're even busier than the boss?
- 你 比 老板 更 忙 ？You're even busier than the boss?
Also note that 更 can be used with 了 in this pattern, indicating change of situation or state, while 还 can't be used in this way.
- 这个 地方 比 以前 更 热闹 了 。This place is even more lively than before.
- 这个 地方 比 以前 还 热闹 了 。This place is even more lively than before.
- Expressing "a bit too"
- Basic comparisons with "bi"
- Basic comparisons with "bu bi"
- Expressing "compared with" with "gen"
- Expressing comparable degree with "you"
Sources and further reading