Phrasal verbs which take objects can be separable or inseparable:
Separable phrasal verbs can remain together when using an object that is a noun or noun phrase.
Separable phrasal verbs MUST be separated when a pronoun is used:
- I picked Tom up. OR I picked up Tom.
- They put their friends up. OR They put up their friends.
Inseparable phrasal verbs always remain together. It makes no difference if a noun or pronoun is used.
- We picked him up at the station. NOT We picked up him at the station.
- They put them up. NOT They put up them.
- We set off for the beach. / We set off for it.
- They are looking after the children. / They are looking after them.