13．About 90 percent of the equipment presented by the administration，as well as the facilities of our own， ______made good use of in teaching．
| A．have | B．has | C．have been | D．has been |
As a matter of fact,his remarks left me ______ about his real purpose.
| A．wondered | B．wonder | C．to wonder | D．wondering |
_______ difficulties we may com across, we'll help one another to overcome them.
| A．Wherever | B．Whatever | C．However | D．Whenever |
So little known _____ that soldiers had to ask for a guide.
| A．by this earthquake - stricken area |
| B．this earthquake - stricken area |
| C．was this earthquake - strcken area |
| D．this earthquake - stricken area had been |
This monument was built in honor of the scientist who was believed ______ the first telephone.
| A．to invent | B．to have been invented | C．to have invented | D．having been invented |
I have kept that picture ______ I can see it every day,as it always reminds me of my university days in London.
| A．which | B．where | C．whether | D．when |