*sweep away*

Definition: to be removed or destroyed by the movement of a river or the sea.

E.g.1. There were some beach huts here, but they were swept away by the flood.
E.g.2. Be careful on the boat – you don’t want to fall in the sea and be swept away by the current.

This phrasal verb can be separated.

*bump off*

Definition: To kill or murder; to assassinate.

Example: 1) Igor got bumped off last week. The police have no clue who did it.

Etymology: This phrase comes from 1920s American gangster slang. When you ‘bump’ something, you give it a little push. ‘Off’ means ‘not on’. So if you ‘bump’ someone ‘off’, you push him toward the end of his life.

Synonyms: rub out

Definition: to fall asleep.

(This phrasal verb has more than one meaning)

E.g.1. Oh! I must have dropped off! This isn’t the TV programme I was watching earlier.
E.g.2. The baby’s mother started to rock him gently, and he soon dropped off.

This phrasal verb can’t be separated.