Bob carried out immediate treatment and reassured the client that the plague would not ______ because the drainage system had been replaced.

A．introduce green cards of their own countries
B．introduce skilled immigrants proportionately
C．create more jobs for the unskilled immigrants
D．try to admit and attract highly-skilled immigrants

A．Europe is more generous to immigrants than the United States
B．immigration may slow down the ageing of Europe's population
C．immigration may lead to instability of the European labor market
D．Europeans will become more xenophobic as more immigrants come in