[判断题]具有择时能力的基金经理一般在熊市时降低现金头寸或提高基金组合的β值。 ( )

In the old days, sending a thank-you note to a relative was easy. You wrote it, (1) , a stamp on the envelope and dropped it (2) a mailbox. (3) it went in a red-white-and-blue U.S. Mail truck, and (4) of days later the friendly neighborhood mailman walked it, (5) . weather, right to the recipient’s door.
(6) you’re as likely to send a fax, e-mail, or instant message. (7) you cling to traditional pen and paper, it’s no longer clear (8) it will travel. Airborne Express Overnight Two-Day Priority
(9) it moves into the 1st century, the American mail system (13) to survive. In the past few years, the U.S. Postal Service(USPS) has (11) many new services, (12) stamps over the Internet, electronic bill payment, and a service that prints and mails electronic documents Yet revenues depleted by alternative communications (e-mail, electronic banking), (13) A. For
B. Until
C. As
D. Since