图中实线是电场线，虚线是某带电粒子通过该电场区域时的运动轨迹，a、b是轨迹上两点，若带电粒子只受电场力作用，根据此图可判断出（   ）

语法填空

    In much of Asia, especially the so-called “rice-bowl” cultures of China, Japan, Korea, ____ Vietnam, food is usually eaten with chopsticks.

    Chopsticks are usually two long, thin pieces of wood or bamboo. They can also be made of plastic, animal bone or metal. Sometimes chopsticks are quite artistic. Truly elegant chopsticks might ____ (make) of gold and silver with Chinese characters. Skilled workers also combine various hardwoods and metal ____ (create) special design.

    The Chinese have used chopsticks for five thousand years. People probably cooked their food in large pots, ____ (use) twigs(树枝) to remove it. Over time, ____ the population grew, people began cutting food into small pieces so it would cook more quickly. Food in small pieces could be eaten easily with twigs which ____ (gradual) turned into chopsticks.

    Some people think that the great Chinese scholar Confucius, ____ lived from roughly 551 to 479 B.C., influenced the ____ (develop) of chopsticks. Confucius believed knives would remind people of killings and ____ (be) too violent for use at the table.

    Chopsticks are not used everywhere in Asia. In India, for example, most people traditionally eat ____ their hands.

草履虫的排泄是通过下列哪些结构来完成的（   ）

Passage B 根据短文内容回答短文后面的问题。

At 5:05 pm on March 19, a loud alarm sounded around the playground of Tanghu Middle School, Sichuan. Students hurried to the playground with something covering their mouths. Don't worry. There wasn't a fire. Students were having a fire drill（演习）. School is a good place for students to study. Yet sometimes, it is easy to have accidents there.

A survey suggests that right safety training could prevent 80 percent of these accidents. In China, fire drills at school are common to teach students to deal with emergencies（紧急情况）. At the same time, many other countries have their own ways to keep children safe around school.

In Japan, public primary schools hold earthquake drills once a month. They teach students safety tips during an earthquake drill. The training teaches students to escape from earthquake-stricken areas without pushing and stampeding（踩踏）.

Most US school buildings have fire escapes on each floor. A fire escape has platforms with stairs and ladders. They are usually made of iron. Students can get to the fire escape through a fire exit door or a window.

In many middle schools in the UK, students can choose to take a bicycle course. There, they learn how to ride to school safely. Also, on roads without traffic lights near schools, there are crossing guards. They wear bright color clothes and stop cars to guide children across the road safely.