- She spends half (of) her time travelling.
- Half (of) my friends live abroad.
We use half of before pronouns.
- ‘Did you like the books?’ ‘I have only read half of them.’ (NOT — half them.)
We use the half (of) to talk about a particular half.
- I think the second half of the film is more interesting than the first half.
half a and a half
Half usually comes before the article a/an, but it is possible to put it after in expressions of measurement.
- I have bought half a pound of apples. (OR I have bought a half pound of apples.)