What is British government’s "tradable certificate" Introduce briefly the dilemma the certificate is now faced with.

A． The British may be said to be conservative, but they are always pioneers in traveling far away.
B． Many English men, women and children would like to choose the traveling destinations in the continental Europe now.
C． Some English people prefer group travels and hotel hooking arranged by travel agency when having an outing.
D． The British people devote themselves to sight-seeing when they are away and purchases are of little importance to them.