The infrastructure of a country is makes everything run smoothly， including things like transport， irrigation， electricity， postal service， telephones and schools.
| A．that | B．what | C．which | D．as |
Mr Blark，________ who we all admire，is a kind but strict teacher.
| A．the one | B．it | C．one | D．as |
Mary's parents admitted that she was always contrary to a wish of ________.
| A．them | B．theirs |
| C．their | D．themselves |
—Have you got any books on English grammar？I'd like to borrow ________.
—Yes，here you are.But you must return it by Friday.
| A．it | B．one | C．some | D．any |
Tom's mother kept telling him that he should work harder，but ________ didn't help.
| A．he | B．which | C．it | D．none |
Being more realistic，the elderly have learned to focus on things that make them happy and let go of ________ that don't.
| A．them | B．it | C．that | D．those |