What technology replaced the vacuum tube as the mechanism for implementing electronic switches in computer hardware

Linux is distributed under gnu gpl. why is this important? a. it ensures that only torvalds can profit from the sale of linux b. it prevents unknowledgeable users from downloading programs they don't know how to operate. c. it provides protection for the developers who created linux. d. it states that anyone can copy, modify, and share the program if changes are made public.

Font size, font style, and are all aspects of character formatting.

Which two technologies support the building of single-page applications?