Mary found _______extremely difficult to pass the examination.

A．It has the largest number of customers.
B．It is grateful for its employees’ efforts.
C．It is successful in the market place.
D．It charges the least for its services.

A．Husbands are paying the social security taxes for their wives.
B．Women working at home can’t get social security.
C．Bosses refuse to pay part of the taxes for female employees.
D．Full-time housewives are required to pay social security taxes.