So it'd be n times n choose n times p to the n, times 1 minus p, n minus n.
所以它会是 n 次 n 选择 n 次 p 到 n,乘以 1 减去 p, n 减去 n。
TED-Ed(视频版)
In this typical NPN transistor, due to certain phenomena at the P-N interface, a special region called a P-N junction forms between the emitter and base.