問題詳情
【題組】47. According to the passage, what kind of signal has long periods of light that are regularly broken bytwo or more periods of darkness?
(A) Group occulting.
(B) Flashing.
(C) Occulting.
(D) Group flashing.
參考答案
答案：A
難度：適中0.692308
統計：A(45),B(6),C(4),D(9),E(0)