1
                             We mustn’t ……………………mobile phone when we drive a car
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            2
                             You ………….obey your parents
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            3
                             People ………………smoke on the plane
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            4
                             Yesterday, he ………………take a taxi to work
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            5
                             I'm really hungry. I ………………eat a sandwich
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            6
                             Sara ………………….wear a coat, the weather is fine
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            7
                             We ………………….. buy sugar , we have much
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            8
                             People ................... follow the rules in public places
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            9
                             For example, drivers .................. stop their cars if the traffic signal is red
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            10
                             At the same time, they ................ talk on their mobile phones while driving
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            11
                             At school, students .............. wear a uniform
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            12
                             They .............. follow the school rules and obey the orders
                     
                                        
                                        
                    
                             
                            
                
                    
                        
                            13
                             On Friday, they ................... have to go to school because it is a holiday