Directions: Complete the following passage by using ONE word that best fits the context.
Deciding what present you should give someone is never easy. Many things must be considered such as
1 the person is interested in and how old he is. We must also consider the reaction 2 the person receiving
the gift. One of the worst gift choices I ever made was for my high school English teacher, Ms Chen. Ms Chen has taught me English since Junior 1, and to show my appreciation I decided to get 3 a present. I asked my
classmates about her interests 4 I made my final decision. Then I went to the department store 5 I worked part-time and bought her 6 expensive gift box of Sichuan beef. I was certain she would like it 7 I had been told by my classmates that she loved hot food. I left the box with a card on her desk, and I was sure she would
like them. 8 was only after I heard she became sick that I learned she couldn't eat MSG!
（3）从木块返回B点到静止在水平面上，摩擦阻力的冲量的大小。