汽轮机转子膨胀值小于汽缸膨胀值时，相对膨胀差为负值。
参考答案：对
Helen has got ________ it takes to be a great tennis player. In other words, she has the potential to become world famous.
A．how
B．what
C．when
D．that
设a、b、c是直角三角形的三边，c为斜边，整数n≥3，求证：an+bn＜cn．
