The lower-level classes （known as subclasses or derived classes） （ ） state and behavior from the higher-level class （known as a super class or base class）.

—Which foreign language are you better at, English or French?—I am sorry I know _______of English and _______of French.

Having a good command of English is（）an easy thing.

Duty is an act or a course of action that people ______you to take by social customs, law or religion.

Project（71）is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

Project ______is an uncertain event or condition that，if it occurs，has a positive or a negative effect on at least one project objective，such as time，cost，scope，or quality．

● Project（71）is an uncertain event or condition that, if it occurs, has a positive or a negative effect on at least one project objective, such as time, cost, scope, or quality.（71）

A declaration made by the Master before a PRC Consul，giving particulars regarding heavy weather or other incidents which may have caused damage to the vessel or cargo，through no fault of the vessel，her officers，or crew is a(n)（）.

Classes at American College　　The year at an American college is divided into 2 semesters or 3 quarters. Semesters are 15 weeks; quarters are 10 weeks. American college students usually attend school from September to May. Occasionally their academic pursuits extend into the summer.　　Students choose their classes a few weeks prior to the start of each term. Universities offer a great many classes in the students’ main area of study and in other areas as well. Students must take both. These include science, mathematics, computer, history and English. Other classes may be just for fun, like dance, theater or sports. Tests usually are given in the middle of the term and at the end3. The final examinations are extremely important. In some classes, the professor asks the students to write a research paper or complete a certain task instead of taking a test.　　Classes usually are organized through lectures. For example, a student may attend 2 or 3 lectures a week by the professor. As many as several hundred students sit at each lecture. Sometimes they also attend a smaller class to ask questions and discuss what the professor says4. These small classes are taught by professor’s assistants. In science classes, students also have a long laboratory class each week.　　What do American students study at college? The US Department of Education says the most popular area of study is sciences and management. Next is social science, which encompasses history, sociology, literature, public relations and political science. English is another popular field of study. Then comes computer science and health and life sciences like biology, chemistry and physics. Education is popular, too. Foreign languages are not popular as a main area of study among American college students. However, students at many colleges must study a language other than English before they can graduate. The most popular foreign language is Spanish, followed by French and German.

Do you like an apple or a banana?（）

（ ）estimating is a technique for estimating the duration or cost of an activity ou project using historical data from a similar activity or project.

During counterflooding to correct a severe list or trim aggravated by an off-center load，a ship suddenly takes a list or trim to the opposite side. You should（）.