For a trade embargo against a particular country to succeed, a high degree of both international accord and ability to prevent goods from entering or leaving that country must be sustained. A total blockade of Petrie’s ports is necessary to an embargo, but such an action would be likely to cause international discord over the embargo.
The claims above, if true, most ply support which of the following conclusions
A．The balance of opinion is likely to favor Petrie in the event of a blockade.
B．As long as international opinion is unanimously against Petrie, a trade embargo is likely to succeed.
C．A naval blockade of Patria’s ports would ensure that no goods enter or leave Patria.
D．Any trade embargo against Petrie would be likely to fail at some time.
E．(E) For a blockade of Patria’s ports to be successful, international opinion must be unanimous.
参考答案：D
解析： 如果用B表示贸易禁运成功，A1表示高水平的国际协调，A2表示阻止货物进出的能力，那么上面整个段落第一句话推理可表达为B→A1A2，第二句话推理可表示为A2→[*]。综合这两句话，可知[*]，所以(D)正确；(A)、(B)、(E)的错误均在于偷换概念，把accord换为了opinion。