单项选择题
The American antelope possesses remarkable powers of sight and can pinpoint potential danger at tremendous distances.()
A.spot B. relay C. attach D. sustain
单项选择题 Why can’t people go very deep in the sea()
单项选择题 According to the last two paragraphs, what did the previous researchers think about the human eye’s light-sensing system()
单项选择题 The history of the exploration of Antarctica recounts many tales of perseverance and suffering.()
