A-A+
In Paragraph 4 the author suggests that the s
问题详情
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
参考答案
正确答案：D
解析：由第四段中的第二句“steam engines that powered the aircrafts were so heavy in proportion to the power that they produced”得知：蒸汽机自身的重量和它提供的动力比例失调。
