Living outside US when applying for citizenship

Hi, my husband is applying for a citizenship and we need help to answer some of the questions. He has had his green card since 1992. For the last two years we were living in Singapore. We came back in July and we are now back in our previous residence. My husband was working for an American company prior to going to Singapore and continued to work for the same company while in Singapore. He paid taxes in USA while staying in Singapore and our home in USA was still our US residence. So then, how does he answer question 6A? Does he say that he lived in Singapore for the past two years or does he answer that he lived in USA for the whole time and only travelled to Singapore (question 7)? (He did travel a few times to USA while in Singapore.) All help is appreciated.

I should mention that I and our daughter (21) are citizens (naturalized) and my son (13) is a citizen by birth.
Thanks