----What do you suppose made her worried ?
----______a gold ring .
| A．Lose | B．Lost | C．Losing | D．To lose |
____ surprised me most was ______ they had finished it so quickly.
| A．What, what | B．That, that | C．What, that | D．That, what |
Maria has to baby-sit. That’s______ she can't come with us.
| A．why | B．ho | C．when | D．what |
--- I rang you at about ten, but there was no reply.
--- Oh, that was probably ____ I was seeing the doctor.
| A．when | B．why | C．what | D．that |
15. _______ all the inventions have in common is _____they have succeeded.
A. What; what B. That; that C. What; that D That; what
This old computer must have been of great use to _______ did the scientific research.
| A．those | B．when | C．whoever | D．whomever |