DI wrote to the White House asking about a birthday greeting for my grandfather who will b

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I wrote to the White House asking about a birthday greeting for my grandfather who will be 95 next year. I received a card signed by Bill and Hillary. They look like real signatures（签名）and are not printed and they are probably produced by autographing（亲笔签名）machines. That says:
Happy Birthday!
Hillary and I are delighted to join your friends and family in congratulating you on this special day. As you look forward to the year ahead, please accept our best wishes for good health and much future happiness.
This was sent in a double envelope so that I could address the inner one to my grandfather and send the sealed（盖章） card to him. The card has the presidential seal printed in gold. The outer envelop is hand addressed. 
NOTE: the postage meter impression on the outer envelope reminded me that the president does not have franking privileges.（邮资特权）
The outer envelope does have a little B written on the upper right corner indication that they have a pile of these pre-signed and double-enveloped; when a request es in, they just write the address on the outer envelope and mail it. 
The return address on both envelopes is simple: The White House, Washington.
73．When did the writer write to the White House?
A．On his grandfather’s birthday.
B．On his birthday.
C．When his grandfather was 94 years.
D．When his grandfather was 95 years old.
74．It’s clear that the card sent by Bill and Hillary was                     .
A．signed by an autographing machine
B．the one that had real signatures of Bill and Hillary
C．the one whose signatures were printed
D．the one that was signed with their own names
75．Form what the card says, we can find it                        .
A．was a public letter for those who were in need of greeting
B．can be sent to all those who write to them both
C．was sent specially to the writer’s grandfather
D．can be sent to anyone whose birthday is ing near
76．The letter “B” on the upper right corner of the outer envelope means              .
A．these are all double envelope having cards with pre-signatures inside them
B．these are all letters which have franking privileges
C．they have written the address on the outer envelopes
D．they have written “The White House, Washington” on both envelopesC