Выделите сказуемое, определите его видовременную форму и
укажите их инфинитив.
what is your brother doing? – he is sleeping
now.

is doing (to do) - Present Continuous

is sleeping  (to sleep) - Present Continuous

Is doing (to do) - present continuous (настоящее , будущее время)
Is sleeping (to sleep) - present continuous too