1.  Have you seen my tablet? I (look) for it for an hour.

Have you seen my tablet? I HAVE BEEN LOOKING for it since breakfast.

2.  Our two sons (live) in this town since 1990.

Our two sons HAVE BEEN LIVING in this town since 1990.

3.  My husband is on a diet so he (eat) sugarfree food.

My husband is on a diet so he HAS BEEN EATING sugarfree food.

4.  A: How long you (drive)? B: For almost twenty years.

A: How long HAVE you BEEN DRIVING? B: For almost twenty years.

5.  Our kids (look) forward to this Disney cruise for years.

Our kids HAVE BEEN LOOKING forward to this Disney cruise for years.