4) How many books about her / he / read / so far

Solution:

To form a question in the Present Perfect tense asking 'how many', we use 'How many' followed by the noun, then the auxiliary verb, subject, and the past participle. 'So far' indicates that the action continues up to the present.

1. How many books about her has he read so far? ('Has' is used for the third person singular 'he'. 'Read' is the past participle of 'read'.)

Answer: How many books about her has he read so far?