And, _________, if you're going to be gone for a while, say on vacation, Dr. Michael Fox suggests you keep in touch with him by email.

A．Seventy-four
B．Seventy.
C．Fifty-nine.
D．Sixty-nine.

A．About 20,000.
B．About 12,000.
C．About 22,000.
D．About 2000.