单项选择题
M: How much is this electronic watch, please W: Five dollars each and nine dollars for two. M: Ok, I’ll take one.
A. 10 dollars. B. 5 dollars. C. 9 dollars. D. 18 dollars.
A. objective B. aim C. object D. subject
A. the Apollo mission was very successful B. protection from space radiation is not a easy job C. astronauts will have deformed children or grandchildren D. radiation is not a threat to well-protected space explorers