It's an unusual thing for us to find ______ UFO.A.a B.不填 C.an D.the 说明选择的原因啊~,今年期末考试题目,想看看自己选的对不对,还有要说明原因啊,

It's an unusual thing for us to find ______ UFO.A.a B.不填 C.an D.the 说明选择的原因啊~,今年期末考试题目,想看看自己选的对不对,还有要说明原因啊,
It's an unusual thing for us to find ______ UFO.A.a B.不填 C.an D.the 说明选择的原因啊~
,今年期末考试题目,想看看自己选的对不对,还有要说明原因啊,

It's an unusual thing for us to find ______ UFO.A.a B.不填 C.an D.the 说明选择的原因啊~,今年期末考试题目,想看看自己选的对不对,还有要说明原因啊,
B
理由：UFO是是抽象名词,不可数,所以可以排除答案A、C
UFO是专有术语但又不独有,象SUN、MOON,EARTH,所以前面不加THE