Tā / suī / rán / shì / wǒ / de / péng / you / dàn / zài / gōng / zuò / zhōng / réng / rán / gōng / shì / gōng / bàn。

他虽然是我的朋友，但在工作中仍然公事公办。

Although he is my friend, he still conducts himself in a strictly businesslike manner at work.