单项选择题

In Paragraph 4, the author suggests that the steam engine used in the earlier aircrafts had failed because ______.

A．they were too small to power a large plane
B．they were too light to generate enough power
C．they. didn't have internal combustion power
D．they didn't have enough power to lift their own weight

<上一题目录下一题>

热门试题

单项选择题

The change in man's size of forehead is probably because ______.

A．only 20 % of the brain's capacity is being made use of
B．his brain has grown larger over the past centuries
C．the other 80% of his brain will grow in due time
D．he will use his brain more and more as time goes on

单项选择题

Which of the following is NOT mentioned as a reason for the Wright brother's success

A．They worked very well together.
B．They both had practical experience building aircraft.
C．They made extensive tests before they completed the design.
D．They were well funded.