Sentence 1: Lisa built a fence around her house. 
 Sentence 3: When Lisa pulled up to it, a sensor would open the gate 
 Sentence 4:  She was thrilled with the new feature 
 Sentence 5:  Lisa felt very secure behind the gate 
 Option 1: She installed a very basic wooden gate. 
 Option 2: SHe installed a gate with a motion detector.