Tourism industry __________ for 200 million people worldwide.

A．They often take place in the major industries.
B．British trade unions are more powerful.
C．There are more trade union members in Britain.
D．Britain has less working days through strikes every year.

A．As soon as she realized that something was wrong.
B．Only when her husband advised her to.
C．A long time after the trouble began.
D．When John asked what was wrong with her.