从每题所给的A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21. Lisa's being admitted to a key university is an exciting moment，_____moment all of her family members will never forget.
A．that B．the C．/ D．a
22. The little boy is very _____: he is interested in a lot of different things and always wants to find out more about them.
A. accurate B. curious C. manageable D. contemporary
