—How long do you think it will be_______China sends a manned spaceship to the moon?

—Perhaps two or three years.

A.when                 B.until                  C.that                    D.before

--How long do you think it will be _________ China sends a manned spaceship to the moon?

   -- Perhaps two or three years.

  A. when          B. until           C. that          D. before

 —How long do you think it will be________ China sends a manned spaceship to the moon?

   —Perhaps two or three years.

   A. when           B. until             C. that          D. before

---How long do you think it will be ________ China sends a manned spaceship to the moon?

---Perhaps two or three years．

1. A.
   when
2. B.
   until
3. C.
   that
4. D.
   before