Traveling can be fun and easy. A vacation trip to another country is especially enjoyable when the traveling conditions are good. Good traveling conditions (11) a comfortable mode of transportation，knowledge of the country's language，familiarity (12) the customs and habits of the people in the country，and pleasant traveling companions. All of US have had nice trips (13) this.

Most of us have also had trips that we would (14) to forget. Many conditions Can produce a bad traveling experience. For example，if the four conditions listed above do not exist，we will probably have a bad experience， (15) at best a difficult (16) . Students who travel to a foreign country to study often have a difficult trip. They usually travel alone. They don't know the language of the new country (17) . They often arrive in the new country (18) a huge international airport. From the airport，they need to find their way to their school. Maybe they need to change airplanes，to take a bus，a train，or a taxi. They need to do all this in a country (19) everything is unfamiliar. Later，after the experiences are over，they Can laugh. But at the (20) ，they feel terrible.

A． include

B． conclude

C． hold

D． contain