A. It cuts down the expenses of dealing with the airport security.
B. It is easy to train the officers with no specialized equipment.
C. It is easier for the officers to identify those criminal acts.
D. It is extremely valid in dealing with immigration violations.

A. Some people use the Internet too much, while some people too little.
B. Sometimes our work online is too much, while sometimes too little.
C. It is impossible for the Internet to supply work regularly to people who use it everyday.
D. The Internet makes people focus on work in the virtual world but neglect that in reality.