DIAO

diao(1)

diao(2)

diao(3)

diao(4)

掉 = diao(4) = to fall down

Or:

掉下去 = diao(4) xia(4) qu(4) = to fall down (of things)

However, please note that 掉 is used only for things, not for people. The word for people falling down is:

摔 = to fall down, to tumble

The more common two-character expression is:

摔到 = shuai(1)dao() = to fall down