Based on the information provided within the question, it can be said that you have to press and hold the CTRL key on the keyboard before clicking each additional slide. This would allow you to maintain the first slide as "selected" while also including various other slides as "selected", in order for you to be able to copy all of the "selected" slides when the copy button is pressed.
Global source and binary. Support for mixed-script computing environments. Improved cross-platform data interoperability through a common codeset. Space-efficient encoding scheme for data storage. Reduced time-to-market for localized products. Expanded market access.