?When did you come back from Beijing?

?_______ the morning of April 18th.

A. At

B. Within

C. On

D. In

--When did you come back from Beijing?

-- _________ the morning of April 18th．

A．At                B．In             C．On

——When did you come back from Beijing?

——             the morning of April 18^th．

A．For               B．On                  C．To                D．At

--- When did you come back from Beijing?

---________ the morning of April 18th.

[　　]