Questions

Those are stairs which goes up and down without moving.

Emphasize means giving special importance or worth giving attention to in speaking or writing.

Here in the options, Accentuate is most nearly means Emphasize.

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.3. The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.29. Together, these three recommendations are often called "triple X"

Dry ice is solid form of carbon dioxide, used as a cooling agent.

It lower temperature than that of water ice and not leave any residue.