When explaining chemical reaction, it may be that, single replacement and synthesis are actually a single factor that contain the mutiple factors of double replacement and decomposition.
When explaining open, it may be that, accessible and continuation are actually a single factor that contain the mutiple factors of hole and space.

I don't know why chemical reaction is single replacement, maybe because of decomposition
I don't know why open is accessible, maybe because of space

When explaining q1n, it may be that, q1s and q1e are actually a single factor that contain the mutiple factors of q1o and q1r.
When explaining q1n, it may be that, q1s and q1e are actually a single factor that contain the mutiple factors of q1o and q1r.

I don't know why q1n is q1s, maybe because of q1r
I don't know why q1n is q1s, maybe because of q1r