侵蚀性葡萄胎最好的治疗方案是
A.单纯化疗B.单纯放疗C.手术+放疗D.化疗为主,手术为辅E.全子宫切除
参考答案:D
某轧钢车间有1台额定功率1450kW,额定转速500r/min的轧钢电动机,电动机的额定电压为6kV,额定容量为1.9MV.A,额定起动电流倍数为5.9倍,额定电压下起动转矩标幺值为1。变电所6kV、50Hz母线上的最小短路容量为46MV.A。起动前母线电压为额定电压6kV,母线上的无功负载为2.95Mvar。起动时母线允许电压标幺值为0.85。机组的静阻转矩标幺值为0.16。试计算电抗器降压起动方案的可行性。
采用电抗器起动时,为保证起动时母线电压降不大于15%,起动时电动机端电压标幺值不能小于()。(选最接近的一个数值)
A.1.12
B.0.85
C.0.50
D.0.42
Looking back on my childhood, I am convinced (1) naturalists are born and not made. Although we were all brought (2) in the same way, my brothers and sisters soon gave up their pressed flowers and insects. (3) them, I had no ear (4) music and languages, I was not an early reader and I could not do mental arithmetic.Before World War I we (5) our summer holidays in Hungary. I have only the memory of the house we lived (6) , of my room and my toys. I can hardly (7) clearly the large family of grandparents, aunts, uncles and cousins who gathered (8) door. But I do have a clear memory of the dogs, the farm (9) , the local birds and, (10) all, the insects.I am a (11) , not a scientist. I have a p (12) of the natural world, and my enthusiasm has led me into varied investigation. I love discussing my favorite topics and enjoy (13) the midnight oil (14) reading about other people’s observations and discoveries. Then (15) happens that brings these observations together (16) my conscious mind. Suddenly you fancy (想象), you see the answer (17) the riddle, and books, of which some might honor with the title of scientific research.But curiosity, a keen eye, a good memory and enjoyment of the animal and plant world do not make a scientist; one of the outstanding and essential (18) required is self-discipline, a quality I lack. A scientist requires not only (19) but also hard training, determination and a goal. A scientist, up to a point, can be made. A naturalist is (20) . If you can combine the two, you get the best of both worlds.
第(4)空应选择()
A.of
B.at
C.to
D.for