1 system for identifying users (on a rail network, the Internet etc)

1 surname Chang

1 frequently

2 often

1 control

2 to exercise control over

3 to contain

1 regular

2 normal

3 ordinary

1 complete change from the normal state (idiom); quite uncharacteristic

2 entirely outside the norm

3 out of character

1 three principles and five virtues (idiom)

2 the three rules (ruler guides subject, father guides son and husband guides wife) and five constant virtues of Confucianism (benevolence 仁, righteousness 義|义, propriety 禮|礼, wisdom 智 and fidelity 信)

1 human nature (idiom)

2 a behavior that is only natural

1 to use foreigners to subdue foreigners (idiom); let the barbarians fight it out among themselves (traditional policy of successive dynasties)

2 Use Western science and technology to counter imperialist encroachment. (late Qing modernizing slogan)

1 to gain the initiative by striking first (idiom); to preempt

2 to anticipate

3 preemptive