重症肌无力患者中有胸腺瘤或胸腺增生占百分之几()
A.10%
B.15%
C.20%
D.25%
E.50%
参考答案:E
Some little boys have difficulty ______their hearts into the lesson for a long time.
A.to put
B.to put
C.putting
D.puting
水轮机导轴承的作用是承受水轮机轴上的径向载荷并传递给基础。