 The key idea is to design a task model that 1) covers a wide variety of household operations and 2) contains human postures to achieve tasks.
<clarity>  The key idea is to design a task model that 1) covers a wide variety of household operations and 2) contains human postures to achieve tasks.
 The key idea is to design a task model that 1) covers a wide variety of household operations and 2) includes human postures to achieve tasks.