I just don't understand_____________ that prevents so many Americans from
being as happy as one might expect.
| A．why it does | B．what it does |
| C．what it is | D．why it is |
Political parties often differ in their views on various _____ concerning their own countries.
| A．ways | B．measures | C．issues | D．patterns |
Evidence obtained from observation and experiment is often used to _____ a scientific theory.
| A．confirm | B．confine | C．conform | D．conceive |
Jack is good, kind, hard-working and intelligent. _____, I can't speak too highly of him.
| A．As a result | B．By the way | C．On the whole | D．In a word |
You can’t guess what difficulty I had_____ your home.
| A．find | B．to find | C．finding | D．found |
As a result of the strong sun, my new dining room curtains _____ from dark blue to gray within a year.
| A．faded | B．fainted | C．paled | D．diminished |