nullable parameter in linq with && operator . How?

fuction void GetBookingSearchCoures(SearchBookingResponse model, int userId, string language, int? _personId = null)
bookingSearches = from uc in _dataContext.V_ENT_BOOKINGS where uc.USER_ID == userId && uc.LANGUAGE_CODE == language && uc.FROMDATE > todaysDateTime
 // here i am trying to append the && with (if not null _personId) //else append the _personId)

How can i do that