在航空竞赛场里,飞机的飞行路径由一系列路标塔指示,在飞机转弯时,飞行员能承受的最

题型:计算题

问题:

在航空竞赛场里,飞机的飞行路径由一系列路标塔指示,在飞机转弯时,飞行员能承受的最大向心加速度大小约为6g (g 为重力加速度).设一架飞机以150 m/s 的速度飞行,当加速度为6g 时,则路标塔转弯半径应该为多少?

考点:向心加速度
题型:计算题

设偶函数f(x)对任意x∈R都有f(x+6)=f(x)+f(3),且当x∈(-3,-2)时,f(x)=5x,则f(201.2)=(  )

A.-14

B.14

C.-16

D.16

题型:计算题

我国历史上,先秦文学以()等体裁为主。

A.散文

B.诗歌

C.词

D.曲

E.戏剧

题型:计算题

如图所示,在磁场中悬挂一根直导线,导线的两端分别连接在电流表的两个接线柱上,组成一个闭合电路.当导线沿着图示方向运动时,有两个运动方向能使电流表的指针偏转,这两个运动方向是(  )

  

A.向右或向左

B.向上或向下

C.向左或向上

D.向右或向下

题型:计算题



Earthquakes often happen near volcanoes, but this is not always true. The centers of some are (1) . The bottom of the sea suddenly (2) . The powerful forces inside the (3) break the rocks. The coast is shaken and great waves appear. These waves travel (4) and rush over the land when they reach it. They are p enough to (5) houses and other buildings; sometimes they break (6) than the earthquake itself.
Very often fires followed the (7) earthquakes. In 1906, the great earthquake at San Francisco broke the gas-pipes. The gas (8) , and soon large numbers of fires were burning in the city. The water-pipes were also (9) ; so it was not possible to put the fires out. There was (10) . The Tokyo earthquake of (11) happened just before the middle of the day. People were (12) on their fires at that time. When the ground shook, the fires shook too. (13) were thrown on the different parts of the houses, some of which were (14) . Soon 134 fires were burning in the city. What kind of building (15) in an earthquake A building with concrete walls is perhaps the best. A (16) will make it even per. The frame holds the (17) together, and the walls do not easily fall. There is (18) of fire because concrete and steel do not burn. The Americans (19) the results of the earthquake in San Francisco, and they are convinced that this kind of building is the (20) .

题型:计算题

可用于人工主动免疫的免疫原是  

A.佐剂

B.类毒素

C.内毒素

D.外毒素

E.抗毒素

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