I think that the Great Wall is worth __________ hundreds of' miles to visit. ...

I think that the Great Wall is worth __________ hundreds of' miles to visit.
A) to travel      B) traveling     C) traveled         D) travel
3. The new staff didn't know how to use the system __________ I explained it to him yesterday.
A) until         B) because        C) if          D) since
4. _______ is reported in the newspapers that the talks between the two companies have not made any progress.
A) That       B) What         C) It        D) As
5. __________by the failure of the project, the manager could hardly say a word.
A) To be shocked        B) Shocked       C) Be shocked    D) Shocking
6. The first question we now discuss is __________ we should go there so early tomorrow.
A) whether        B) where       C) what         D) whom
7. He was attending a meeting, _______