1.The human brain has 100 billion neurons and up to 150 trillion synapses.
up to多達
I can take up to four people in my car.
我的汽車最多能坐四個人 。
2.By contrast, human intelligence developed through evolution, which is a much slower process.
by contrast相比之下; 相形之下
The private sector, by contrast, has plenty of money to spend.
相比之下,私營部門就有很多錢可供開銷 。