Sentence Correction

by kamrul
(Dhaka, Bangladesh)

Is following sentence correct?

Roni's mother absolutely hated nicknames and always calls her by her full name.

I think this is wrong. Please let me know

2.Only after they had completed an exhaustive study_______________ how to adapt the technology to the needs of the company.

which of the following is correct in the gaps

a) did they begin to understand
b) they did begin to understand.

I guess a is correct.

3. Is the following sentence correct?

Whenever I can't spend time with my friend, I always speak to him on the phone.

I think this is correct.