The difference between the afternoon high and the evening low is greatest in （）

单项选择题According to the forecast, （）

A．Kansas City will be warmer than Toronto
B．temperatures will be the lowest in Seattle and Minneapolis
C．the weather will be fine in most of the listed cities
D．more than half of the listed cities ore cloudy or rain likely

单项选择题How is the 1996 discovery related to the possible existence of organisms on Mars

单项选择题What were the Mars' seasonal changes in color believed to be

单项选择题A variety of extracurricular activities are added in American schools （）

A．to help students climb the education ladder
B．to enrich students' dull life at school
C．to help students become more successful in later life
D．to extend college education down into elementary schools

单项选择题Which of the following can be the best title for this passage