阅读理解。
Directions: Read the following passage. Complete the diagram by using the information for the passage.
Write NO MORE THAN 3 WORDS for each answer.
For many years, parties have been an important social event. When 25 people or more gather at a certain
location in order to have fun and engage in conversation, it can be considered a party. Parties usually have
different drinks and food choices, and music is a large part of the event, very often.
Birthday parties are held in honor of an individual who is having a birthday, and presents and gifts are
usually brought by attendees (出席者).The song "Happy Birthday to You" is very often sung by partygoers
for the person who is having a birthday.
There are different kinds of Birthday parties. Adults may have birthday parties in restaurants or nightclubs, while children usually have parties at home or at funhouses. Sometimes children may have parties at water
parks or amusement parks, as well.
Birthday parties may also happen in the manner of a surprise party, where the person having a birthday is
not told about the birthday preparations. Surprise parties include guests hiding in a location where the party is
to take place, then shouting"surprise!" when the guest of honor enters.
Sporting event parties usually take place around a specific sports happening, such as the Super Bowl, the
World Cup or the World Series. People gather and eat, drink, and laugh as they talk about the happenings of
the games within that sporting event. These types of parties are very lively and usually loud.
Nightly socialization parties include house parties and dance parties. House parties sometimes are held by
teenagers and young adults of college age in a set location; private houses are often the location of choice.
People who manage the music are hired to provide musical entertainment. Usually alcohol is included, resulting
in trouble for the attendants of the party.
Dance parties include energetic music like disco or pop. People gather at these parties to dance, drink, and
have a good time. Usually people at these parities will be of younger ages between 18-28.
，从A点移至B点，电荷克服电场力做功
。试求： 
，若把这一负荷从B移至C电场力做多少功？是正功还是负功？ 
，故电势能增加了4.0×10-4 J
