[单项选择]We are all for your suggestion that the trip ______.
A. is to put off
B. was put off
C. should put off
D. be put off

From 1946 until 1954, the Vietnamese had struggled for their independence from France during the First Indochina War. At the end of this war, the country was temporarily divided into North and South Vietnam. North Vietnam came under the control of the Vietnamese Communists who had opposed France and who aimed for a unified Vietnam under Communist rule. The South was controlled by Vietnamese who had collaborated with the French.
The United States became involved in Vietnam because it believed that if all of the country fell under a Communist government, Communism would spread throughout Southeast Asia and beyond. This belief was known as the "domino (多米诺骨牌)theory." The U.S. government, therefore, supported the South Vietnamese government. This government’s policies led to rebellion in the South.
In 1965 the United States sent in troops to prevent the South Vietnamese government from collapsing. Finally, however, the United States failed to a
A. Vietnam War is the military struggle fought in Vietnam from 1959 to 1975, involving the North Vietnamese in conflict with the United States forces and the South Vietnamese army.
B. In 1965 the United States got involved in the war in order to prevent the South Vietnamese government from collapsing.
C. During the conflict, approximately 1.5 to 2 million Vietnamese on each side were killed and more than 58,000 Americans lost their lives.
D. The U.S. government supported the South Vietnamese government and its policies led to rebellion in the North.