Faced with nuclear pollution, we think it is time to the trip to Japan.
A. call in
B. call for
C. call off
D. call on
网友回答
A. call in
B. call for
(答案→)C. call off
D. call on
解析：词义辨析。call in叫某人进来；call for需要，要求；call off 取消；call on
号召。句意：面对核污染，我们认为是时候取消到日本的旅行了。所以选C。