Ответ:

1)

How long have you been writing books?

- I've been writing them for five years.

2)

How long have you lived in Africa?

- I have been living there since 1998.

How long has your guide been working with you?

- He has been working with me for two years.

3)

What else had you been doing in Africa?

- I had been taking pictures for my guidebook.

How long has the travel around Kenya taken you?

4)

I had been traveling until 6 a.m.

- Have you been walking around Kenya?!

I have been driving and walking.

5)

Have you been riding elephants too?

- No, I haven't ridden on elephants. But I had sent pictures of elephants and many other animals to magazines.

I have sold most of my photos.  

I'm thinking of becoming a full-time photographer.

I have been thinking about changing my job for two years!