题目内容：

阅读下面短文，从短文后各题所给的四个选项（A、B、C和D） 中，选出可以填入的最佳选项。

It has been about forty years since the invention of post-it notes (便利贴). These sticky notes, as people often________ them, can be used to mark a ________ in a book. They can be used to ________ a note to a report turned in to a teacher. They can even be used to post a reminder note in a place where it will be       . Many people question how they were invented. The       is surprising because the discovery was actually a(n)       .

In 1968,       Spencer Silver was working with different types of adhesives (胶). He was trying to develop new       for a company that created and sold clear tape. One particular adhesive just would not       for long periods of time,       it could be peeled off easily. He passed the       around the company to see if anyone could find a(n)       for it. Nobody could imagine a way to use an adhesive that did not stick to a       permanently.

Six years later, Art Fry, another scientist with the same company, became frustrated while ________ with his choir (唱诗班). The piece of paper he used to mark his place on his music kept        . Fry wished he had something that would make the paper stay in place.       , he remembered the________adhesive Dr. Silver had passed around. Fry wondered, “Would it be possible to use the adhesive?”

It turned out to be quite        ! Applying the adhesive to the back of a piece of paper made the paper stick wherever it was placed.       , it didn’t stick permanently. The paper could be easily        . Thus, the sticky note was born.

1.A. make       B. suspect       C. prove      D. call

2.A. secret      B. character      C. place      D. plot

3.A. lift        B. attach         C. introduce  D. carry

4.A. filled      B. caught         C. noticed    D. repaired

5.A. answer     B. evidence      C. result     D. method

6.A. mistake     B. accident       C. difficulty  D. assumption

7.A. scientist   B. manager        C. reporter    D. businessman

8.A. customers   B. habits         C. plans       D. products

9.A. wait        B. exist          C. stick       D. behave

10.A. if         B. though         C. as          D. so

11.A. tool       B. invention      C. tape       D. equipment

12.A. use        B. explanation    C. cover      D. name

13.A. book       B. surface       C. door        D. company

14.A. competing B. traveling      C. singing    D. standing

15.A. coming back B. falling out   C. breaking down D. rolling up

16.A. Surely    B. Naturally     C. Frequently  D. Suddenly

17.A. unusual    B. hard          C. cheap      D. effective

18.A. possible   B. horrible      C. funny       D. quick

19.A. Again      B. Later          C. However  D. Besides

20.A. returned   B. found          C. read        D. removed