how to select multiple value in form dropdown

how to select multiple value in form dropdown using DayPilot.Modal.form.

code :

 const form = [          
          {
            name: 'Start Date',
            id: 'start_date',
            type: 'date',
            dateFormat: 'd/M/yyyy',
          },
          {
            name: 'End Date',
            id: 'end_date',
            type: 'date',
            dateFormat: 'd/M/yyyy',
          },  
          {
            name: "Choose mission task", 
            id: "Choose_mission_task", 
            options: tsk,
          },
          {
            name: "Work Shift", 
            id: "work_shift", 
            options: listed_shifts
          }
        ];