The millions of calculations involved, had they been done by hand, ______________________ (恐怕早就失去了所有价值) by the time they were finished.

A．He doesn’t know what tools to bring.
B．He doesn’t mind helping the woman.
C．The woman won’t have to carry tools.
D．The donkeys will carry the woman’s personal items.

A．law
B．rule
C．case
D．matter