Now many manufacturers build their business reputations by enclosing ______ in the new products in case of damage in shipment or by incorrect operation.

单项选择题There have been several attempts to introduce gayer colors and styles in men's clothing, but none of them（）

A．has caught on
B．has caught him out
C．has caught up
D．take roots

单项选择题Every member of society has to make a （）to straggle for the freedom of the country.

A. pledge
B. warranty
C. resolve
D. guarantee